WHAT ARE THESE

[toneB]

Are they reef and tank safe

 

[KJ]

Sponge reef safe

 

[toneB]

They all in my overflow

 

[Lynn52]

You tend to get them in a new tank. They need silicates so when the silicates go down their numbers go down. For the first couple months after I set up my tank they were every where the fish couldn't get to them,overflows, sump,and skimmer. I still have some but not many mostly in my sump and overflows. They are harmless filter feeders.