Is butyl rubber caulking fish safe?

"Grandpa" wrote in message
...
I am making my own bio filter and have some butly caulking. Would this be
OK to use?

Thanks.


My rule of thumb with sealants is that if it doesn't say it is safe for fish,
don't trust it. I would use a sealant approved for the use. Aquarium sealant
should work fine, as long as you let it dry completely before using the filter.