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Red Firefish
12/02/2007, 11:14 PM
Hi everyone. I posted this in the plant forum in more detail, but thought I'd ask a larger audience:

Does anybody dose phosphates to their reefs to supplement photosynthesis? I'm referring specifically to using it to stimulate algae growth in the refugium setting, but I suppose if anyone was phosphorus-limited in their reef they might have a way of dosing it.

Is there a supplement that people prefer over Seachem's Flourish phosphorus? Thanks all!

SeanT
12/02/2007, 11:15 PM
Do you add iron as well?

Red Firefish
12/02/2007, 11:26 PM
I've thought about it, but I don't dose it regularly. I don't have an iron test kit that I trust, or a pure iron supplement (Seachem's Flourish Iron is Iron gluconate, which I believe is organic). I do weekly water changes with a blend of Oceanic and Instant Ocean salt, both of which contain iron.

Also, if I were to overdose iron, there isn't a convenient chemical resin to remove it, so I'm a bit more wary of dosing it.

wrott
12/02/2007, 11:39 PM
There is so much phosphate in food that the answer to your question is yes, 2 or 3x / day. I feed flake, pellets, frozen--several varieties of each. And I run a phosban reactor w/ lots of algae growth.

adtravels
12/03/2007, 04:05 AM
again I dose phosphate twice a day, flake in the morning, frozen in the evening:D

King-Kong
12/03/2007, 06:50 AM
I'm pertty sure your in-home reef is never short on phosphate.... not much is needed, and we tend to have way more than we need.

Now as for nitrogen and carbon.. that tends to be a bigger issue.

Zifer
12/03/2007, 09:14 AM
i would not do it..doesnt sound like a good idea...

glassbox-design
12/03/2007, 09:17 AM
depending on your N or P levels, whichever is limiting can be dosed to increase chaeto growth and lower the other.

e.g. Nitrate's are high but po4 is low. If proper flow and lighting is given to the chaeto, a small amount of Kpo4 can be dosed into the refugium allowing the chaeto to uptake the dosed po4 and the no3 that's produced by the tank.

hth.

pkmg
12/03/2007, 09:35 AM
Dosing phosphates and Nitrates is done with planted aquariums for the goal of reducing algae growth. Basically in the past few years it was found that in ideal conditions the plants will out compete the alge for the nutrients, and that doses will even reduce algae growth.

I do not believe you could create the same relationship in the reef aquarium.

Red Firefish
12/04/2007, 08:15 PM
<a href=showthread.php?s=&postid=11303828#post11303828 target=_blank>Originally posted</a> by Flint&Eric
depending on your N or P levels, whichever is limiting can be dosed to increase chaeto growth and lower the other.

e.g. Nitrate's are high but po4 is low. If proper flow and lighting is given to the chaeto, a small amount of Kpo4 can be dosed into the refugium allowing the chaeto to uptake the dosed po4 and the no3 that's produced by the tank.

hth.


That's exactly the idea. It's been about 6 months since I began doing it. Nitrates weren't high before (around 10), but after adding the plant tank to the system it kept climbing while phosphate stayed undetectable. Dosing phosphate dropped the nitrate to less than 0.2, so I think it's worked well.

I guess KPO4 is still the preferred method. I didn't expect I was the only one, but that's ok. Thanks for all your replies!

m2434
12/04/2007, 08:37 PM
What else do you have in your system? The problem I see in a reef tank is that phosphate can inhibit coral calcification even at very low levels.

glassbox-design
12/04/2007, 08:50 PM
you're should dose directly into the algae filter to allow better "absorbtion". the minimal and temporary amount shouldnt effect the corals imo. when po4 is dosed it is because po4 is the limiting factor so the a raise from .o1 to .o5 should be ok.

are there any studies to show at what po4 level that can occur? could be a good guideline for those doing this...?

Snowboarda42
12/04/2007, 09:05 PM
+1 on the Food=phosphate

I'd be happy if all my chaeto died off due to lack of nutrients

Randy Holmes-Farley
12/05/2007, 06:42 AM
I would second dosing of iron long before I'd try dosing phosphate, unless it was a tank that literally did not get any fish food.

Seachem Flourish Iron is a fine way to go. The ferrous gluconate in it is, IMO, about perfect. I have used it, but now buy it at a local drug store (not much cheaper, but I'm sure of the concentration). Many people growing macroalgae have seen immediate benefits from dosing iron, including the owner of Reef Central.

There is no need to measure iron when dosing it.

This article has more:

First Iron Article: Macroalgae and Dosing Recommendations
http://www.advancedaquarist.com/issues/aug2002/chem.htm

and

Second Iron Article: Iron: A Look at Organisms Other than Macroalgae
http://www.advancedaquarist.com/issues/oct2002/chem.htm

Red Firefish
12/05/2007, 10:26 PM
<a href=showthread.php?s=&postid=11316507#post11316507 target=_blank>Originally posted</a> by m2434
What else do you have in your system? The problem I see in a reef tank is that phosphate can inhibit coral calcification even at very low levels.

I keep mostly stony corals in the reef tank. SPS corals are domninant, but I also keep several LPS and a few soft corals (mostly zoanthids). The plant tank is not intended just as nutrient export, but as an aesthetically nice display that works in synergy with the reef. There is a healthy amount of calcification in the reef display despite my phosphate additions to the plant tank.

you're should dose directly into the algae filter to allow better "absorbtion". the minimal and temporary amount shouldnt effect the corals imo.

I dose the KPO4 into the refugium as you suggest, and with the pumps off for about 30 min. The plant tank (approx. 15% total system volume) spikes to 0.3 phosphate when I dose with KPO4. This amount, spread over the entire system, tests at 0.03 (Salifert) after 60 minutes mixing, and 0.00 the next day.

I would second dosing of iron long before I'd try dosing phosphate...

Mr. Holmes-Farley, thank you very much for taking the time to weigh in.

The articles on Iron were exciting and informative, and I will begin experimenting with Flourish Iron immediately. I am particularly interested to see how it affects the cyanobacteria within the reef display. As I mentioned in the plant forum, I have noticed that when I forget to dose phosphate for a week or so, cyanobacteria begins to grow in the sand. I have assumed that this was due to phosphate limitation, while nitrogen and carbon were still available at testable levels. Perhaps iron will produce some noticeable change as well.

I am curious- you mention in the first article that iron likely precipitates out of solution if overdosed; would you suspect any potential detriment from allowing this precipitate to accumulate through chronic dosing?

Also, congratulations of winning MASNA hobbyist of the year. You received quite an ovation from those of us at MACNA in Pittsburgh. Thanks for your help!

Randy Holmes-Farley
12/07/2007, 02:56 PM
Interesting that you observe cyano when not dosing phosphate. I can't really think why that would be relative to nutrient limitation in other organisms.

Also, congratulations of winning MASNA hobbyist of the year.

Thanks! :)

glassbox-design
12/07/2007, 03:32 PM
redfirefish, glad to hear it has worked out for you. the cyano popping up does sound strange though. are also adding any type of carbon source the cyano could be utilizing?

congrats on hobbyist of the year. i didnt even know there was such a thing :D

scolley
11/13/2009, 09:55 PM
I'm pretty new to reefs, but have been mulling over this idea for some time. Not because I'm interested in stimulating algae growth in my refugium as the OP suggested. That would be a by product.

The reason - in my case - would be to reduce nitrates.

depending on your N or P levels, whichever is limiting can be dosed to increase chaeto growth and lower the other.

e.g. Nitrate's are high but po4 is low. If proper flow and lighting is given to the chaeto, a small amount of Kpo4 can be dosed into the refugium allowing the chaeto to uptake the dosed po4 and the no3 that's produced by the tank.

hth.
Exactly! And that's what I've got - unmeasurable phosphate, and nitrates stubbornly fluttering from 3-6 ppm. So while I cannot say that phosphates are the only limiting factor, with a reading of zero, it's definitely one.

And since my refugium has chaeto on a light schedule opposite that of the DT, if I dose it with little enough phospate in the evening, it could all be gone by the time the DT lights go on in the morning.

And the beauty is that it should pull nitrate out at something like 10 times the rate of phosphate. So a little phosphate could go a long way toward nitrate reduction. Or that's how I see it anyway.

So my plan is to start adding a wee bit of KH2PO4 to my refugium every night. Just enough to raise the phosphates from 0 to .01 ppm. Maybe less. And if I can read ANY phosphates in the morning, I cut back on the dose, but not until it drops to zero again. And hopefully I'll be able to find the sweet spot soon (as far as the dose goes) and slowly start chiseling away at those nitrates.

With the small daily water changes I do, there should always be a bit of iron in the water. And for this small amount of photosynthesis, I'm hard pressed to believe the chaeto will not get all the carbon it needs from CO2 equalization with the ambient air.

If it works, I'll post the results. ;)

Randy Holmes-Farley
11/14/2009, 07:03 AM
OK, we're looking forward to seeing what happens! :)

scolley
11/14/2009, 08:34 AM
Thanks Randy. ;) I know this stuff is difficult to prove without controls. But this test does have a few things going for it:



I've had f/w planted tanks for years. I know how to dose, and how to dose with a reasonably high level of precision.
My tank is somewhat stable. My calk/alk does drift more than I would like inside of what I think of as the "Holmes-Farley" box. But never far. And never out of it.
The at 5 months in, this little 29g reef is in "maintenance mode" now. No more fish additions. No more inverts. Just slow, steady growth.
I keep decent records that I'm happy to post.


On the down side, this tank is almost totally free of nuisance algae. I do get the occasional bubble every couple of months, but that's it. So if I see ANY increase in algae (easy to spot when there's none, and it's a small tank), I'm pulling the plug and buying some GFO. :D

So we'll see. It won't be definitive. But it should be a decent data point.

scolley
11/18/2009, 09:23 PM
Brief update:

I dosed sufficient for a 0.01 ppm daily Phosphate increase for 2 days. The result was an outbreak of bubble algae, a measurable amount of phosphate (roughly 0.03) and my cessation of the test. For now.

I still think this is a very valid pursuit, and that there were errors in both my testing methods, and in my assumptions. Yet I still believe that my original premise - that excess nitrate can be safely reduced by phosphate dosing IF phosphate is the limiting nutrient, and IF the phosphate is dosed low enough to be absorbed by inverse-DT light cycle macro algae within a single photoperiod - is still valid.

But that requires a lot more discussion. So in deference to the OP, I'll start a new thread soon, post detail results there, and encourage discussion on that premise there. Once I get my phosphates in check again. ;)

Will post a link to that thread here, once I start it. :)