Running a seagrass tank in conjunction with an sps tank need some advice.

[graveyardworm]

My dilemma is that the sps require a very low nutrient environment and seagrasses seem to need a fair amount. I realize that I cant place the nutrients in the water column for the seagrasses so I would like to take advantage of their ability to remove nutrients from the substrate. I would like suggestions and folks with experience to help guide me through what to dose and how much. As I understand in the wild seagrass beds have a substantial amount of rotting organic material in and around them. Obviously I cant duplicate that. Any suggestions?

[TheH]

I think some people have suggested freshwater substrate fertilizing tabs in the past.

[graveyardworm]

I think some people have suggested freshwater substrate fertilizing tabs in the past.

Any worries with heavy metals in those?

[TheH]

I think most of the heavy metals in those tabs like iron, potassium, magnesium, etc. are okay for our purposes. Are you talking about impurities?

[3D-Reef]

I tried some fertilizer plant sticks and they quickly overwhelmed the system,so if You try them just remember a little goes a long way.

IMO I don't think as much organic material is needed as one might think.In one study there was seagrass growing in substrate with as little as 0.5% organics.But from reading several other ones I gather that it's the bacteria, which support the grass,by releasing inorganic N & P,and the conditions by which they are in determine how well the grass does.

[graveyardworm]

My grasses have been hit or miss for awhile. The best growth I've been able to achieve was when I ran the seagrass tank skimmerless. Now that I've hooked it back into my main system growth has slowed tremendously. I'm still adding the same food to the seagrass tank for the fish in there, but with the low water column nutrients its not helping. 3D, you seagrasses have been growing strong for awhile now. I'm not sure that I even know what you're keeping in your display. Are you still dosing iron to the sand bed, anything else?

[3D-Reef]

The DT is mixed,SPS's,zoa's,sponges,clams,seawhips,ect..
I did try injecting iron and the results were more shoots,that effect lasted about month and a half.But I didn't follow up with another round.After that I replaced part of the bed with laterite in the bottom layer,and months later in another section I used GFO.So I haven't had to dose iron for about a year now.I think that the laterite is a better substrate mix than the GFO,even though they used GFO in one field study.

It seems that iron does a couple of things.They found that Fe is limited in carbonate systems,this in turn limits the bacteria converting free N & P.They also found that Fe "attracts" P.In other words P is limited in places where Fe was limited.Although the addition of Fe in low organic substrates didn't increase the bacteria activity,it did increase the shoot production.
The dilemma is that the bacteria,actinomycetes and mycorrhiza,are in the cyanobacteria family.So improving conditions for one does the same for the other.Talk about a cyano-bloom.;) But I've since started dosing MB7 in low doses and the cyano has cleared up.
FWIW In places of low nutrients (N) in the water column,the plants concentrated on thicker root production with fewer shoots.Where as the places with a higher nutrient content didn't store as much in the roots and was able to put up more shoots.But in most cases P was still the limiting factor.

[Plantbrain]

DTPA Fe works well, dose 2x a week at 0.1ppm.
A few Osomcoat pellets under each plant can be done also.
Clay balls etc also with whatever mix of ferts you want.
Tweezers and place them next to roots.



Regards,
Tom Barr