Mhay
Crazy Cat Lady
The amount of antibacterial compound absorbed by rock & sand, if any, would be an incredibly small amount. Any tiny residual amounts would be flushed over time. I wouldn't worry too much about it. The proof will be when you do a new cycle after fixing the silicon in the sump. When ammonia & nitrite go up, then down to zero, you know for sure you have a functional bacteria colony.
I would change out a large percentage of water after putting any animals in a QT tank, fix the sump & start a new cycle. RO only - no tap ! You may find the cycle to be much shorter than the your initial cycle. Good luck, sorry to hear of your issue but hang in there. It's worth it!
Thanks! Tonight I'll be draining everything tearing down the sump and overflow and start again. We have a whole bunch of RO/DI water made this time ready to go. Needless to say I learned a very valuable and expensive lesson.
