Silicone crash

[ScubaSteve]

The mildew inhibitors are petroleum distillates. The only thing that will remove them is aspiration by a skimmer (basically "undissolving" them) and big water changes. They don't stick to carbon. The silicone may also be leaching ammonia if it didn't cure long enough. Add an ammonia absorbing pad.

Pull the sump and rebuild it. Sorry you got bitten by the GE silicone problem. Seems to be getting pretty common and it's a pretty easy mistake to make. GE didn't even list the petroleum distillates in their MSDS until recently as they were a trade secret.