Would like to convert FOWLR tank to sea-grass

[davidpt40]

I have a 40gallon tank right now that has a few damsels and clownfish in it. It also has some homemade live rock and about 4 inches of southdown sand in it. Lighting is a 400w metal halide.

I would like to convert this mundane looking tank into a seagrass bed. I know that seagrass requires lots of iron and probably a few other nutrients, so what would I need to do in order to convert it?

Is southdown sand an appropriate substrate?

If I stock this tank with only a few fish and lots of inverts (like a natural seagrass bed), what type of mechanical filtration would I need?

Are there any alternatives to buying expensive iron/nutrient supplents?

Thanks-
David

[billsreef]

Southdown is an excellent substrate size for sea grasses. Your 4 inch depth is also workable. How old is the tank and sand bed? Aged organic rich sand beds seem to do the best. In newer sand beds you can use fertilizer tabs such as those used by FW plant aquarists. IME and from talking to others, Iron seems like a crucial element for sea grass growth. Haven't found a way around that one yet ;) As for mechanical filtration, I would only use what is necessary to keep your carbon from clogging with debris. Minimal mechanical filtration makes for more interesting planktonic life forms that can help support many filter feeding inverts.

[piercho]

"Are there any alternatives to buying expensive iron/nutrient supplents?"
I use the Kent's chelated iron, I forget the exact name. For my 70G system, a $8 bottle will lasts a long time. I dose less than the recommended amount on the bottle. I prefer to dose small amounts of iron frequently, rather than large amounts infrequently, because I have this notion that iron gets bound quickly in the aquarium into a form that is not available to plants.

[davidpt40]

Sandbed is about 8 months old. Someone suggested I increase the sandbed to about ~6 inches deep, is this really necessary? The tank is a 40gallon and the heater is already nearly touching the sand. As it is, the sand depth ranges from 4 to 5 inches.

[billsreef]

4-5 inches will work just fine ;)