Red slime in seagrass biotope

[Gastro]

I have a 3 month old 45g seagrass biotope tank (macroalgea, not real seagrass). It has a 1" fighting conch, 4 tiny hermit crabs and a larger crab. It also has a prizm deluxe skimmer, 96w of PC light, 40w of NO flourescent, and 1 penguin 660 powerhead (172gph). Red slime algea is taking over the tank. It grows all over the sand, and I have to remove it every day. It is smothering my macroalgea and growing all over the conch's shell. What should I do to get rid of it? I would prefer biological control, but I don't know what animal will eat it. Maybe some sort of snail but I have hardly any rock for them to climb on, so astrea is ruled out. What do you think?

Thanks,
Andre

[rshimek]

Hi Andre,

The only animals that eat the red slime algae are conchs such as the fighting conch you all ready have.

A seagrass tank without seagrass is not a seagrass biotope. It is a algal growth tank.

How deep is the sand layer and did you add animals such as sand-dwelling worms??

[Gastro]

This is my first tank so I didn't want to get seagrass. No, just the conch, hermits, and the larger crab. The sand is about 4" deep. The macroalgea is taking a lot longer to grow than I thought, and now it it just red slime over everything

Thanks,
Andre

[rshimek]

Hi,

Without the appropriate animals for the sand bed, it will simply become a place where decomposition of detrtitus can occur, this will foster the growth of the red cyanobacteria. The macroalgae have to compete with the cyanobacteria for nutrients, and they generally lose in this battle, hence they will not grow as rapidly.

At this point, I think about the easiest thing to do would be to seed the sand with some live sand animals (you would have to remove the hermit crabs and crabs as they will eat these animals). Periodically you will have to siphon and remove the red slime, it will take quite a while, but it is possible to regain control of the situation.