Caribbean Biotope Seagrass Tank
 

Greetings Saltwater Plant Experts!

I've been reading all the threads here on RC regarding marine planted tanks, and I must say, you guys are taking the hobby to another level! A lot of the biochemistry stuff goes right over my head, but I'm starting to get a feel for it. Some of these concepts are brilliant! For instance, dosing nitrate to balance its ratio to phosphate in a tank, thus favoring the plants over micro algae, that's way cool! So I know I'm in the right place to discuss my ideas for a Caribbean Biotope Seagrass Tank.

First, let me tell you a little about myself, before we get down to the dirty details. I started on the marine side in about 1993, with a 60 gallon cube with bleached coral skeletons and some pretty cool fish. In 2002, I began planning my dream reef tank. I ended up with a 240 gallon Eco-Wheel tank and a custom-built cabinet that I designed. When the economy tanked (sorry) in the late 2000's, my income dropped a lot, so it became increasingly difficult to justify the costs. Plus, I came to the realization that I might not be obsessive-compulsive enough to reach my goals as a reef keeper.

So, after some soul-searching, I decided to trade in my reef fish, corals, inverts, etc. for a Fresh Water Planted Tank. Much more affordable! For example: cost of fist-sized coral - $100, cost of a fist-sized plant - $5! And the aquascaping was much more interesting. So that's where I am now, with a pretty sweet freshwater planted tank setup.

But, like most of us in this hobby, I find it hard to leave well enough alone!

So here's what I'm thinking…

A Caribbean Biotope Seagrass Tank, with a deep sand bed, almost no live rock, lot's of manatee grass, a few sponges, gorgonians and anemones-and all endemic to the Caribbean! I want to combine everything I've learned from reef-keeping and plant-keeping.

I've also got lots of ideas regarding fish, plumbing, lighting, aquascaping, etc. but the first thing I'd like to discuss is the SUBSTRATE for the manatee grass.

I've got about 4 inches of very mature Eco Complete (a fresh water plant substrate) in the tank now. I'd like to use this as the foundation, so to speak, of my seagrass substrate. I've read that seagrasses like a rich, muddy, sandy substrate. So I'll mix in some fine aragonite and top it with progressively coarser sand, shells and rubble.

So, has anyone tried Eco Complete in a seagrass tank? Does anyone know of any reason why I shouldn't use it?

I look forward to your thoughts!

Thanks,
Michael

Substrate for Seagrass
 

Ok, so I did some research on Eco Complete. It's basically a lava-based sand/gravel of varied sizes. It's also basically inert, so doesn't directly contribute any nutrients. But it does have a high CEC, or cation exchange capacity, which (I think) means it can absorb/store nutrients that are added and release them as needed. Which I'm guessing (hoping) is a good thing.

So, overall, I'd say that Eco Complete is not as good a substrate as I'd hoped, but not a bad choice as a percentage of my substrate makeup. What I think helps favor MY Eco Complete, is the 5 or 6 years of accumulated mulm I've got in there. Yay pooh and stuff!

I'd welcome anyone else's thoughts, experiences, insights.

I really want to get this right, because I think getting the seagrass established is going to be one of the biggest challenges of this tank.

Following! Can't wait to see pix. This tank is going to be gorgeous.

Sounds good! I can't see any reason why eco complete won't work either, just make sure to get live sand. You will need the worms and other infauna that come with it! Also, if you haven't already read it, take a look at this article: http://www.chucksaddiction.com/The%2...art%20Two.html. It has lots of great info on seagrass beds.

Seagrass Article
 

Wow! That was quite an article! Very helpful. Thanks JLynne!

One part I found particularly fascinating was about the different substrate compositions:

"The ability of a substrate to provide the essential dissolved nutrients has been shown to be determined by the composition of the sediment (Short 1987) in of its composition, either terrigenous (land-based eroded rock) or calcium carbonate. The grain sizes also determine the nutrient dynamics involved. It has been shown (Erftemeijer 1993) that Indo-Pacific, near-shore sediments comprised of terrigenous material has a significantly higher pore water concentration of nitrogen compounds than the calcium carbonate-based sediments while the reverse is true of phosphorous compounds."

So, the terrigenous substrate (like my eco-complete) holds more nitrogen, and the calcium carbonate substrate holds more phosphate. Having a good combination of these two substrates would seem to combine the best of both worlds. Also Eric Borneman's tip of using freshwater plant tabs to help the seagrass get started sounds like a great idea.

So here's what I'm thinking…

My substrate will have (more or less) 4 layers. Bottom layer: mulm-rich eco-comlete plus plant tabs. 2nd layer: very fine aragonite sand blended with eco-complete. 3rd layer: very fine aragonite sand. Top layer: a combination of fine and coarse sand, seashells and rubble.

I want to tip the balance in favor of the seagrass over the microalgaes, in the early phase of the tank. One of the strategies I learned from the freshwater plant side of the hobby, is to plant heavily, with fast-growing plants (along with the plants you really want) in the initial setup of the tank to get a leg up on the microalgae and cyanobacteria. As a variation on this technique, I may introduce lots of Manatee Grass, which is the plant I really want, without any other plants, which could compete with it. I want a large, monospecific seagrass bed in this tank. I'll introduce a crew of Astrea and Cerith snails to help out as well.

However, I'm tempted to follow Mother Nature's example and start with the pioneering species like oar grass and shoal grass. Once these get a foothold, I THEN bring in the Manatee Grass.

Another thing I noticed in the article was that he said that in the Indo-Pacific, the seagrasses had to take up almost all nutrients through their roots, because the water there is nutrient-poor. I wonder if caribbean seagrasses have more water-borne nutrients to work with (that will certainly be the case in my tank).

Thanks to all whom have read along so far. I invite you to chime in with your two cents!

You're welcome! To the best of my knowledge, the main advantage of using pioneering seagrasses first is that they are shorter-lived than species like Thelassia Sp., so they build up a helpful layer of nutritious detritus in the sediment when they die. For that reason, it is worth considering. However, you mentioned that your eco-complete is very mature and has a lot of detritus built up in it already, so in your case the pioneering species of seagrass may be redundant.

That thing about the nutrient-poor water column of the Indo-Pacific got me to thinking. What if I could emulate that in the initial phase of my tank? Isolate all the nutrients in the substrate to favor the seagrass, and keep the bulk water very low in nutrients to keep the algae at bay! Easier said than done right? Well, I don't plan to introduce ANYTHING before the substrate and seagrass. I do plan to bring a refugium online at some point. If I went ahead and brought it online from the start and stocked it with chaeto and ulva, that could help to keep nutrient levels down in my tank water, right? Sounds like a plan!

I know some of you are thinking "what about the live sand critters?" I plan to introduce them right after the seagrass - on the same day.

Thanks, Whiterabbitrage for the encouragement! As soon as I have something to show, I'll post pics. As I'm still in the planning/dreaming phase, it'll probably be a while. In the meantime, there's much to discuss!

I do want to try and savor every step in the process, rather than rush through to get to the final result. I must say, I'm really enjoying this part - so many ideas swirling about! Now that I'm getting older and more experienced, I hope I have the patience to do this thing right.

As I've been compiling Caribbean wish lists of flora and fauna, I'm also thinking about the species of 'me'. I think a lot of us fail to consider ourselves in the equation. What are my characteristics as a mesocosm-keeper? I have to admit I'm kinda lazy! I like to use my big 'ol brain to figure out ways to save on labor. My favorite labor-saving device is NATURAL PROCESSES.

Does anyone out there remember reading Charles Mathews M.D.'s column, 'Reef Science', in "Freshwater and Marine Aquarium" magazine? His catchphrase was "Less technology, more Biology". He was all about using natural processes rather than gadgets. He also set up experimental aquariums to test all kinds of theories. I found this fascinating!

One of the things I was thinking about as I read through the "old favorites" in the Invert and Plant Forums, was the 'Nitrate to Phosphate Ratio'. Planted tanks with fish in them get plenty of phosphate through feeding and fish waste, so they tend to be nitrate-limited, right? Of course there's carbon and iron and other trace elements to consider as well, but for now I just want to focus on the N to P ratio. So the solution is to dose nitrate, right?

So I went to "the krib" website to check out their Poor Man's Dosing Drops formula. As I looked for that formula, I came across an article dated Sept. 1995, by Charley Bay, called "Nitrate Factories are Stupid". This article (rant) pretty much summed up the thought that started the move away from trickle filters back in the day.

Do you see where I'm going with this?

As I see it, I have two choices here: I can go to town and find all the ingredients for the PMDD, mix it up and start adding daily dosages to my tank, OR, I can go up in the attic and dust off the "'Ol Nitrate Factory". Yep, I'm seriously considering putting my trickle filter back into service! And IF it turns out to work, I'm going to write an article titled "Nitrate Factories are Freaking Brilliant".

One unfavorable comparison I can think of is the fact that with dosing, you can adjust the N ratio pretty easily to suite your tank's needs. I suppose I could adjust the number of bioballs in the trickle tower to raise or lower the amount of nitrate produced in "the factory". Hmm…

OK, so am I missing something? Please, someone, shoot this theory down before I make a fool of myself!

The problem with that plan is that there is nowhere to buy these "live sand critters." The only way to get these infauna is to get them with the sand, and for the long-term health of your sand bed, it is vital that you do. These creatures won't add nutrients to the water column; they have their own food web in the sand. On that note, do not get one of those sealed bags of sand that is called live sand. What they mean by that is that it contains bacteria. You will need to order your sand online in order to get the good stuff (eg the sand with bacteria and worms and other sand-dwelling creatures vital to your tank).

JLynn, there is a source for sand bed critters without the sand. Indo-pacific Sea Farms (ipsf.com) They have all manner of sand dwelling creatures, including worms, mini brittle stars, tiny clams and what not. Inland Aquatics (inlandaquatics.com) also carries them. I probably will buy some caribbean live sand as well. I found a source in Florida that sells actual live sand from the ocean, so I'll have some sand specific to my caribbean biotope.

I think I'm going to add the top 3 layers of sand AFTER I place the manatee grass on/in my bottom layer, so as to avoid doing any damage to the roots. I'll mix in that Florida live sand with the top layer and then I'll introduce the pods, worms, etc.

Oh, I wanted to thank you for your thoughts on the pioneering seagrass idea. I agree that, with all the mulm I've already got, they may be redundant.

I will follow your efforts so please keep us posted with pics. Went snorkeling in Mexico once over grass beds and was blown away by the beauty of it, but I spent a lot of time on planted tanks and discovered I had no real talent for it so I won't try one myself.

There are unique animals in an environment like this. That is one of the things that could make it really special.

Thanks for the post, HoustonHobby! Yes, I'll post pics when I have something to photograph. Right now I'm still looking at my quickly overgrowing freshwater planted tank…

I guess the first thing I'll have to photograph is kind of an oddball project for the new tank.

I've got one of those Tunze powerheads that is mounted on the top of the tank, so it hangs down into the water, looking rather unnatural. And I'd really like to not have ANY visible plumbing or gadgets in the tank. But I also really want to keep that powerhead right where it is.

So I'm going to build my own aquarium ornament to hide it. What kind of ornament? Well, in keeping with my caribbean biotope theme, I'm going to sculpt a mangrove stump with roots. The top part of the stump, which will extend up a little above the water level, will be hollow, so as to accommodate the powerhead. The roots will arc out reach down into the substrate.

If you google mangroves, check out some of the images. The roots of these trees are just beautiful! I hope to capture some of that beauty with my fake stump…

Sounds good! The ceramic will have the added benefit of housing more bacteria. I do love mangroves. I only wish I had the patience to grow one big enough to recreate that environment!

The 'Ol Nitrate Factory
 

I'm still hoping to get some comments on my idea of using a trickle filter to save me the trouble of dosing nitrate. As I said before I'm kinda lazy, and I know from experience that I'm not likely to keep up with daily dosing.

Also, any thoughts on using chaeto and ulva in the 'fuge right from the start to keep water column nutrients to a minimum, while the seagrasses suck up nutrients from the substrate? I thought this strategy would help to minimize that early microalgae phase.

I'd appreciate any thoughts, ideas, suggestions you might have.

If you can find it,there was a study done by Jose Gonzalez Liboy (2005)on the Caribbean grass Thalassia,t.It has just the info Your looking for.

From the study....41% is sand,17.5% silt,32% clay with small amounts of quarts.In an other study they found that there was 80% calciumcarbonate,~18% mag-calcite,~2% nutrient rich mud/soil.

The only thing I see,that might be problem,is that if you put too much nutrient rich material in the substrate it can,and most likely,will go anoxic and kill the grass.

One other thing,most seagrass beds tend to become more richer in nutrients over time.So if you start out with a very rich environment,then it can become eutrophic in a short period of time.

Thanks, 3Dreef. I'll see if I can find that study.

Basically, it sounds like you're suggesting I use less organic-rich substrate (my aged eco-complete), to avoid anoxic conditions (nearly zero oxygen) in the sand bed and eutrophic (nutrient-heavy) conditions too soon, rather than letting them build up naturally, correct?

I would expect anoxic conditions at the bottom of my sand bed, that I estimate will be around 7 inches deep. But I wouldn't expect that to kill my seagrass. Can you elaborate? I would imagine that in nature anoxic conditions exist at similar depths without it doing harm to the grasses.

That's a very good point about eutrophic conditions too quickly. Maybe I'm trying to give them too much of a good thing too soon? And I definitely don't want all that stuff seeping out into the water column right away and causing eutrophic water conditions! Algae-fest!

I'm hoping that my 4 layer substrate plan allows a wide gradient of oxygen levels through its depth, while keeping the really nutrient-rich area at the very bottom, and not up in the water column.

And just in case, my fuge with chaeto and ulva should help in that regard.

Thanks for your insights! More please!

3DReef, I found that study and I'm reading it now. Thanks for the info!

I read the study on thalasia in Puerto Rican waters. In it there was a good chart of sediment composition in different areas. So yes, not a whole lot of mud in there. I wish he had discussed it a bit more. The seagrass article from Chuck's Addiction had some really informative discussion on the application to our tanks, plus a good quote from Ron Shimek:

"Sediments - The seagrass refugium's sediment is vital to the health and long term survival of the seagrass just as it is in natural meadows. How you construct the sandbed is going to determine its functionality in providing a nutrient rich environment for the seagrasses rhizomes and root structures. Seagrasses are plants that depend upon their roots for the uptake of nutrients, roots that require extremely fine grain sizes, it will be imperative that a calcium carbonate substrate with grain sizes ranging from 0.2 - 1.02mm be used with a depth of no less than six inches, deeper if possible. Incorporating a live mud into the sediment during the sand beds construction will ensure a suitable number of infauna are introduced. Just as in nature the infauna are critical to the functionality of any sandbed to process nutrients and prevent the formation of sand clumps by their movement through the sediment (Shimek 2001)."

Your welcome!

Correct.

It's not so much that the lack of O2 causes harm to the plant,(the plants have a way of around that) but, it's more about what is happening in an anoxic environment that gets 'em.:D
Seagrass plants, more or less, depend on/need too interact with the bacteria there to release nutrients too them.They are kinda lazy in that aspect.They could do themselves,but at a cost.So,if there are more bacteria/nutrients than what the grass can support with O2/NO3 the bacteria then turn too SO4 (sulfate).
When the bacteria start using SO4 ...the end result is Hydrogen-sulfide,or bi-sulfide.This gas is highly toxic to everything alive including plants.
Basically it will suck out any oxygen from anything alive.This is what kills the plant.

Tip of the day:D
"First,it has to be acknowledged that seagrasses seem to be adapted for growing in nutrient-poor environments.Not only the mechanisms described in the first sections of this chapter (nutrient resorption,use of poor water nutrients,storage,ect.) allow these plants to better use nutrients,but also it has to be considered that seagrasses require approximately 8-50 times less nitrogen and 1.5-100 times less phosphorus for daily growth than macroalgae or phytoplankton,respectively (Daurte,1995)."

I agree,Shimek is an expert on sand beds and infauna and I give Him all due credit and respect,but,even He Himself will tell you He's not up on grasses and there requirements.With that said...Seagrasses can and do uptake nutrients from the not only from the substrate but from the water column as well.Equally I might add.
So IMO,it would be easier to manipulate nutrients in the water column than in the substrate.Because once it's in there...it's there until you tear it down and start over.

My fake Mangrove Root Pics!
 

Ok, so I'm posting pics for the first time, so bear with me.

Here are some pics of the very beginning phase of my fake mangrove root project. I hope you can see them well enough to tell what's going on.

http://www.reefcentral.com/forums/pi...ictureid=61511

IMG]http://www.reefcentral.com/forums/picture.php?albumid=8941&pictureid=61510[/IMG]

http://www.reefcentral.com/forums/pi...ictureid=61514

http://www.reefcentral.com/forums/pi...ictureid=61513

Hopefully everything shows up!

Well, 3 out of 4! I thought the captions would show up as well.

The first image shows the basic armature (skeleton) of the mangrove root. Those are plastic bottles forming the main root, and wires forming the smaller roots. The small wooden arm extending horizontally just marks the depth of the sand bed at 7.5 inches.

Second image is a crude sketch with the mangrove to the right.

Third is the two-part epoxy clay I'll be covering the armature with. It's non-toxic when dry. It's gray so I may paint dark brown when it's done.

Thanks again, 3DReef for the very helpful info. I tend to agree, so I guess I'll be using less of my eco-complete than I had originally planned. I remember reading about those beneficial bacteria that help out the roots with nutrient uptake. I do expect there to be anoxic conditions at the bottom of the sandbed, but I won't put the seagrass' roots that deep.

My Fake Mangrove Root - Foil Stage
 

Here' a couple of pics of the root with foil on it. The foil looks weird but it does help to visualize it.

http://reefcentral.com/forums/pictur...ictureid=61532

http://reefcentral.com/forums/pictur...ictureid=61533

I'm pretty happy with it so far! Working with the foil is pretty easy - just tear off a sheet and wad it up around the wire. This'll help bulk it up so I don't run out of epoxy clay.

I had to modify the design as I went. I had to compress it front to back so I'll be able to get it under my hood and into the tank. Next I've got to make sure it'll work with my powerhead!

More changes to fit the powerhead inside. Also I got rid of the main root, after looking at mangrove pictures again. I'm thinking of replacing 2 liter cola bottle with 5" PVC to make it a more rigid structure. I'm also considering building it in separate pieces, so getting it in the tank will be less challenging. It's amazing how many complications pop up as I go along!

Nice thread! I too am starting a manatee grass biotope, but mine is a 29 gallon RDSB sump for a 75 gallon reef tank. I went with a 2 inch thick layer of ~5mm crushed shell at the bottom to fight anoxic conditions, a 4 inch thick middle layer of ~1mm arogonite sand for the root structures, and a 1 inch layer of sugar fine oolitic on top to keep detritus from clogging the system too quickly. For initial nutrients, I've placed a very few small pieces of plant spikes. Since this sump is a settling tank for a larger system, I believe no further fertilization will be required. ASW replaces many micro nutrients with each water change, and macro will come from display waste. I was able to seed the sand with a few cups from another display, plus i seeded with sand i collected from a manatee grass bed. I too am considering bio balls, but I'm going to wait and see how my nitrate settles after my cycle matures. If my display macro algae limits nitrate, I'll just add bio balls upstream the sand bed. The only thing I've learned so far, on this setup, is that I should have waited to add the grass. if I use the strong light that the grasses need, pest algae and diatoms explode due to the nutrient rich new tank water. If I dimm the light, the grass yellows out and dies back. I'm only about a month in, and I've lost half the height of my grasses. Luckily, the roots I've checked are still pearly white. I would recommend adding the first grasses after your tank has had a few months to mature.

Thanks, SecondsBest for sharing your experience. You said you were about a month in right? Is your display tank the same age, or is your seagrass sump the only new element? What do you think is the source of nutrients in your "nutrient rich new tank water"? The substrate? The display tank? I was planning to plant heavily with seagrass from the start to outcompete the algae. Do you think this is a mistake? It seems to me if there are excess nutrients in the water, why not plant early? If you don't, then there is nothing to compete with the algae.

I'd appreciate any other thoughts you have. And I look forward to hearing your results when you implement the bio balls!

It'd be great to avoid that early algae phase. But is it really possible? Even when I planted heavily in my freshwater tanks I still got algae while the plants got established. I'm guessing this happened because I may have added fish too soon and/or I covered the eco-complete with only a light layer of gravel, allowing nutrients to easily enter the bulk water. I hope to avoid those mistakes with this tank.

I've read that seagrasses get the majority of their nutrients through their roots, just like terrestrial plants. I'm going to try to confine most of the nutrients to the substrate and keep the water nutrient-poor. Also, per discussion earlier in this thread, I'm going to start with a less nutrient rich substrate than I had originally planned. Wish me luck!

Any suggestions are greatly appreciated!

This 75 gallon display tank, and the 29 gallon sump, are new. I also have a 20 gallon down stream of the 29. The 20 has a shallow sand bed of about 15 pounds oolitic, plus 20 pounds of reef ruble, all established for six months on another tank setup. The 20 also contains my skimmer plus the evicted tenants from my other tank. For the display, I put in 100 pounds dry rock, and then I added 10 pounds live rock from my other tank. The display is bare bottom. I consider the water nutrient rich because I had heavily stocked the display with macro algae I collected locally. By heavily, I mean a 5gallon buckets worth. It was also packed with thousands of inverts. A good part of this died off, kick starting my new tank cycle. I then removed most of the macro algae, leaving some specimens, plus all the inverts to establish. At the one month point, my parameters for the nitrogen cycle are all good (all undetectable, including nitrate), but I'm sure the dry rock needs more time to establish. Green film, red hair, and diatoms are growing faster than my macros. Grass stems have died back, but the rhizomes are growing. From my experience, this is just a continuing part of a new tank cycle, and I would rather not worry about nursing the grass while I did nutrient export. I think your plans are still workable, but I wouldn't expect explosive macro algae or grass growth up front. That may be more evident for you since you don't have cured live rock or sand in the works. As for the bio balls, I will only add them if I don't see grass and macro growth, and if nitrates remain undetectable; otherwise, I prefer to keep nitrates low for the corals that I will add to the display in another month or so.

Tell us a bit about the two buckets of mix to make mangroves. I have always wanted to do a mangrove edge tank but thought I would use bent PVC pipe and make then look more real with a bit of that sculpting mix.

Great info Secondbest, thanks. I see how you are going through your new tank situation with a heavy nutrient load - a tricky situation!

I hope to avoid the nutrient heavy water in the beginning by not adding fish or curing live rock in the tank. So this tank will be a bit different than a new reef tank or fish only setup. I agree I shouldn't expect explosive seagrass growth at first. I've just got to be patient.

I really learned a lot from the "Old Favorites" threads. Some of those grass and macro folks had little to no fish loads, so they were dosing nutrients, which of course seems insane to reef keepers! Adjusting the ratio of nitrate to phosphate is pretty mind-blowing stuff. Have your read any of those threads?

Since you said you have near zero nitrate, but still nutrient-heavy water, maybe your N to P ratio is off. Maybe you should consider cranking up the nitrate factory to help your plants export the phosphate.

Well, JPF, one is the resin, one is the hardener. You mix them at a one to one ratio to get the clay, then you sculpt. Since I've never used it before I don't have much else to tell at this point. Once I get my hands dirty, I should have more to say about it. I look forward to sharing the experience!

I think using PVC should work well. I'm probably going to replace my plastic bottles with PVC myself to get a sturdier structure.

I'm figuring it out as I go. With all my design constraints (fitting a powerhead inside it, getting it under my hood), my project is much more complicated than just sculpting the root. But I like a challenge and the more I fool with it, the closer I come to finishing this thing.

So I want to get it right the first time, so I don't have to do it again!

Oh, also, I started a new thread on my fake mangrove root in the DYI section.

I would suggest that you try carbon dosing in order to 'kick start' the plants.Rather than nitrate dosing or allowing nitrate to build up.

Thanks, 3d-Reef, I will. I have a CO2 setup for my freshwater planted tank, which I originally bought for my calcium reactor for my reef tank.

I don't plan to add nitrate until my seagrass gets nitrate limited. This shouldn't happen until some time after my sand bed matures and/or I add fish (and feed them) and phosphate levels rise, throwing the N to P ratio out of balance.

I've been thinking about how to make my old trickle filter adjustable. As the seagrass gets established, I expect it's ability to uptake nitrate will grow. It would be cool to make the trickle tower 'modular', so I could add height and bio balls as needed.

It may need inorganic C after it has become established...I was suggesting dosing organic C until does become established.Like what happens in an older seagrass bed.The grass provides OC to the bacteria,in turn the bacteria release P too the plants,and denitrification of N03.

What would you suggest I dose as a good source of organic carbon? Or maybe something I could include in the substrate from the start?

About two and a half years ago I completely tore down the grass tank one week and set it back up the next weekend with new sand(above ratio). I used plain 'ole white vinegar for dosing.Dosing to the water column does make it's way down into the substrate to an extent.
With in two months I had new shoots coming up.

Thanks, 3d-Reef. Oh yeah, vinegar! I've read a good bit about the carbon-dosing craze. A very interesting concept-and proven to work if done right. I had thought about applying the concept to feeding sponges and gorgonians and possibly flame scallops, instead of exporting the excess bacteria with a skimmer.

I had not thought of carbon dosing (other than CO2) for my grass. So you think it would help establish the beneficial bacteria that assists the roots with nutrient uptake? Did you dose vinegar right after you re-set up you grass tank? Did you use a skimmer for export?

Well...if you think about it.An establish grass bed produces two things during photosynthesis.Oxygen and sugars (organic carbon).
When you transplant plants there is a time when they are in shock.During this time frame they have to use up stored carbohydrates to convert No3 into a useable form (NH3). With the help of bacteria of course.

My thought was to supply the organic carbon so the reserves would not be used up too fast so the plant won't slowly die over a couple of months and it would also help get the bacteria to become established.
Does that make sense?

Yeah,I started dosing vinegar a few days after I set it back up.Yes I do run a skimmer for export of the excess.

You mentioned a few posts back that once you build the substrate the nutrients that are in it are there for life so you plan to just manipulate the nutrients in the water column.

As a former planted tank person I think this may be a mistake. First, nutrients do move back and forth between the water column and the sand bed. But more important, if your seagrass is used to getting nutrients from the sediments then forcing it to compete with nutrients only in the water column is probably a bad idea.

In the water column, all sorts of micro and macro algae can get at the nutrients, probably easier than the sea grass can. To help the sea grass outcompete these undesirables, you need to help them out by feeding the roots.

One thing that planted tank people do is put nutrients into clear gell caps (the sort of thing health food stores carry) and then push them into the substrate near the roots of the plant they want to feed. I think you should consider something like this.

Thanks,
Rod

HoustonHobby, I agree. I think that was someone else who posted about feeding the water rather than the substrate. I want my water as nutrient poor as is practical for this application.

Basically I want to start this tank doing everything I can to favor the seagrasses and starve the algae and cyanobacteria. I want to confine the nutrients to the substrate as best I can. I like your idea of using gelatin caps to fertilize the roots. Sort of like the plant tabs, but you're able to custom-taylor the nutrients you want in there.

I'm going to set up a refugium as well with chaeto and ulva to help soak excess nutrients.

I am currently a freshwater plant person myself, with a 240 gallon tank with metal halide lighting, CO2, and a whole lot of plants! As I've been planning this new tank, I've been letting the plants get out of hand!

As I said back in the beginning of this thread, this tank started as a reef tank, then I changed over to FW planted. Now I want to combine what I've learned on the reef side and the FW planted side to make this SW seagrass dominated tank.

Here's a pic of my current tank, left 2/3s of it.

http://www.reefcentral.com/forums/pi...ictureid=61668

I appreciate your thoughts. Keep 'um coming!

You obviously have the talent for this. None of my planted tanks ever looked that good. Thanks for the pic.

Wow thanks, HoustonHobby for the compliment! You made my day.

By the way, what did you put in the gel caps for your plants?

Seagrasses out compete algae by recycling what little nutrients that are available to them.The less there is in the substrate...the less there is too leach out into the water column.
The plants already uptake from the water column.It's how they compete with algae.By sucking the nutrients down below what algae can survive.

If you put in more nutrients than what the plants need to recycle.Your only going to feed the algae/cyano.
Just saying.

I never made caps of my own. I bought them already made from a guy on the plantedtanks forum who made them up for fresh water. I have no idea if salt water formulas would be different but I doubt it. I bought dry ferts from some place I can't remember but it is an easy google. I used them to dose the water column but you could put them in caps easily. I got gell caps from amazon prime and use them myself for medical purposes.

Thanks 3D-Reef. That really is the key I think. How much nutrients to provide the seagrass at startup, to give them a head start without giving algae what it wants. It seems to me that putting the nutrients deep in the sand bed, while minimizing water column nutrients is a good solution. I agree that they will leach out into the water, but hopefully that will take some time, and give the seagrass a head start.

You said before, once you put something in the sandbed, it's there until you break down the tank. I get your point but on the other hand, I've added heavy nutrient input to my freshwater planted tank substrate, using plant tabs. The plants suck them up and grow like weeds, then slow down as the tabs get used up. I pushed them down about 5 inches deep, and I did not notice any uptick in algae production in the tank. I'm sure some leached out, but overall the strategy worked. My plants outcompeted the algae.

I realize of course these are different plants, but I know that plants will use nutrients that are available to them, even if they are adapted to nutrient-poor conditions. Diana Walstad did some experiments that proved this pretty convincingly. Her book "The Ecology of the Planted Aquarium" is excellent.

I do agree with you that putting too much of my aged eco-complete in there would be a mistake. I'm just going to have to (re)read all I can find about seagrass substrates in nature and come up with my own secret sauce. If I recall, some exist in nutrient-poor substrates and some in nutrient-rich ones.

I think our biggest difference of opinion is on the seagrass' ability to take up nutrients from the water column. Here's my point of view: these are higher plants with separate components that do different things. Basically, the roots take up nutrients and the leaves photosynthesize. They are not macroalgae, which are much simpler plants that do get most of their nutrients from the water column. So in my opinion, feeding the roots and not the bulk water is the best way to favor the seagrass.

I'm just going to start thinking out loud here...as someone with ZERO firsthand experience growing seagrass, but is coming from a similar place as you (FW planted tanks) and is trying to start a seagrass tank. I'm also a "soil scientist" with specific interests in aquatic/wetland systems, so I have some theoretical background as well.

Even the fine ecocomplete is supposed to be around 0.5-3 mm, which actually may be a bit coarser than what you could see in a typical seagrass bed (depending on the location, you'd obviously want to focus on the Carib. areas). I'm honestly not sure how much of a difference it would make, but you probably wouldn't want to overdo it compared to some finer grains.

Regarding the nutrient issue, yes, "higher order plants" have roots for a reason but when it comes to aquatic plants that doesn't mean it's their exclusive means of nutrient uptake. The aquatic environment is different than the terrestrial, where water conservation is at a premium.

Interesting article I found with a quick (emphasis on quick) Google search: http://www.int-res.com/articles/meps/134/m134p195.pdf

Pesky kinetics aside, it seems that (for this particular species and location at least) leaf uptake is oftentimes needed because the availability of nutrients in the soil is a bit more complex and not always sufficient. Of course, this does ignore 1) root tabs that are placed strategically will likely better target root uptake over what's just there in the bulk soil and 2) the fact that I'm sure this system is NOT algae free ;)

I do understand the concerns with dosing nutrients that are accidentally available for unwanted algal/bacterial growth...but at the same time water column dosing is, at least in my opinion, far easier to quantify and monitor because water chemistry is a bit more straightforward than soils...and that's particularly true when you look at what methodology is available for hobbyists. I'm sure you're also familiar with many dosing strategies in the FW world that advocate for "overdosing" the water column, and I've seen algae-free tanks using that method as well. But usually those are essentially tanks on steroids, pumping out huge growth rates with high light and carbon supplementation...

Me? I always get algae, no matter what it seems...I've resigned to that fact despite the fact that I can spew all this theory without anything to really show for it. I think it's an interesting topic, for sure...people will be "debating" nutrients and aquariums forever :D

In any case, I'm following what you're doing with this setup, whichever route you take, because I'm jealous you get to do this on a much, MUCH bigger scale than I...

jpappy789, it's funny because I was just reading articles online, and the one you mentioned was one of them. It seems seagrasses are adaptable to varying conditions, allowing them to use their leaves for nutrient uptake if they are more bioavailable in the water than the sediments.

I also reread some chapters in Diana Walstad's book "Ecology of the Planted Aquarium" and found some tidbits I'd forgotten. She is referring to fresh water plants, so I don't know whether these assessments are also true for salt water seagrasses. Paraphrased, "Aquatic plants, unlike terrestrial ones, prefer ammonia to nitrate. They have to convert nitrate to ammonia at a significant energy cost. Aquatic plants prefer to uptake phosphorus from the substrate via their roots. They prefer to uptake potassium and ammonium through the water via their leaves".

What would really be helpful for me is info pertaining particularly to manatee grass, which is what I want to grow. I guess it's back to the internet!

I agree it's fun to go on about scientific theory, but the proof is in the pudding! I will keep researching, but I still think that at startup, I want to favor substrate nutrients over water nutrients. After the grass gets established (assuming I don't kill it), I will experiment with dosing the water vs the substrate, using the gel caps and different nutrient formulas.

I don't want so much to 'overdrive' plant production as 'coddle' them when first planted. From my experience with fresh water planted tanks, I see this as the most challenging phase. Over time I want them to settle into an equilibrium with the conditions in my tank. Eventually, I should be able to determine which nutrients are limiting growth and dose those.

It's ironic that such a relaxing hobby as aquarium keeping can turn you into an amateur scientist! I wish I'd more attention in school…

I believe Ms. Walstad is correct about NH4 vs NO3...generally the former is preferred in N assimilation depending on what's available.