Seagrass Questions...

[Fishfreak218]

OK,
well here is my questions.. if seagrass takes up its nutrients from the sand via its roots then if there is nitrate in your water it wont help the seagrass at all?? How do you guys test your sandbed for all the right elements?? do you just test the water??
thank you
-josh

 

[Samala]

It will take up nutrients both through roots via the substrate and through the leaves directly out of the water column. That's how I mainly feed my plants.. water column dosing of ferts. The general wisdom to use an aged or fertilized substrate for a seagrass bed is great advice for those that will not be dosing ferts and want to run a more lagoon (lean) tank. This way you keep water column values low, but the plants get what they need from the substrate.

It is possible to test pore water from substrate (the water inbetween the sand grains) by using syringes mainly, but I dont know if its really necessary. What are you thinking of doing to the sandbed?

>Sarah

 

[Fishfreak218]

I was just wondering how you guys knew if your Seagrasses were getting the right nutrients.. because i thought that they only get them from the substrate...
thank you VERY much
also is there any key stuff that they like/need besides Nitrate???

 

[Samala]

I've stuck seagrass into very fine, and very inert, glass beads, and had it grow very well with only water column dosing. It works!

Key stuff: lots. Have you seen the seagrass article on Reefkeeping? I think I got into detail about it. Mainly, they need carbon (CO2 or alkalinity), light, nitrogen and phosphorus in large amounts. Possibly also potassium, but that can come from the seawater itself. The smaller nutrients they need ("micronutrients") include things like iron, magnesium, calcium and then very small amounts of others, copper, boron, zinc, etc.

Typically I find those micronutrients can come from water changes with a good salt, the bigger stuff can often come from the bioload and an aged sandbed.

>Sarah

 

[Fishfreak218]

thank you very much... thats pretty much what i was expecting....
when you say nitrogen and phosphorus do you mean nitrate, and phosphates????

 

[Samala]

Yep. Nitrate is a source of nitrogen and phosphate is a source of phosphorus, but they're not the only ways of getting N or P to the plants. For us, they're likely the best ways. Consider ammonia, ammonium, nitrite.. all usable by the plants. You dont want them in the tank though.. the pest algaes love them even more for fuel than the plants do!

>Sarah