Black Slime

[jtipton]

I am setting up a 55 gallon brackish tank and moving my decorations from my 20 gallon. The salinity is at 1.010, and the 20 gallon uses a calcium based sand substrate called "Grey Coast". The depth is around 3-4". I removed some of the larger rocks and placed them in my new 55 gallon tank. When I removed the rocks, the underside of each one was covered with a black slime. I want to use the deep sand beds for better filtration, so how can I prevent this slime? Is it a cyanobacteria? What will eat it? I chose not to remove the black slime because I am trying to use the rocks to speed up the cycle of my 55 gallon setup. I thought cleaning the rocks would defeat the purpose. Will this cause a problem in my new tank? Any help is appreciated.

Thanks,
Jason

 

[Colin_T]

The black slime is usually cyanobacter or blue green algae and is caused by excess nutrients, low oxygen levels and poor water movement. It is not nice stuff and should not be put in the new tank because it inhibits the good bacteria. Wash any rocks or ornaments before moving them to the new tank and syphon out any of the blue green algae every time you see it.