Can someone tell me what this is?

[messeduptriple]

I've been having this growing in my rock for sometime now ..its hard when I touch it but I have no idea what it is?? I now noticed there's another small one growing on another rock..anyone know what this is? Thanks.

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[notbad]

from the picture. I believe it is a sponge. not sure the true name. but have them all over my rocks. well not all over mostly were the lights dont hit

[SushiGirl]

+1 on sponge

[Grace tank]

+2 on sponge

[aleonn]

+3 sponge. They're good filter feeders, but I've sometimes seen relatively large outbreaks in tanks that use de-chlorinated tap water. I think I read that may be due to high silicate levels, but someone correct me if I'm wrong.

[messeduptriple]

Declorinated? I just use regular tap when water changes.
I looked somemore and have found 1 smaller 1 just starting to grow and I think one that's webbing and I think that's the start of the sponge I'm guessing?? Are they harmful or a good thing?

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[SushiGirl]

You aren't removing the chlorine from tap water when putting it in a fish tank???

[aleonn]

Sponges are good, beneficial filter feeders.

I'd get an RO/DI unit for the best water quality, and convenience of having to go to the LFS with 5 gallon tanks. If not, then at least use Seachem Prime, Amquel/Amquel Plus, Chlor-Am-X, or one of those dechlorinating solutions if using tap water. Chlorine and chloramines are toxic to fish livestock.

[messeduptriple]

I'm using aquasafe...I really don't know if its actually working...I'm guessing it is? Nothing is dieing for a few years now.
Well except for a clam..that was upsetting

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