ABS Bubbling up...suggestions wanted

[Flatlandreefer]

I have a thin sheet of ABS on the bottom of my bare bottom nano tank. I used silicone to secure it to the glass but I must have not gotten very good coverage in one spot. The ABS is bubbling up in one spot and it needs secured. I need opinions on the best way to do this. I am wanting to avoid emptying the tank. Would superglue work, this seems like it would be the fastest method of curing. I don't know if silicone is even an option in a tank with water and livestock?

 

[ndrwater]

Silicone is not an option since the tank is full of water. Super glue MIGHT work, but could be messy.
Have you thought of placing a relatively heavy rock in the offending area?