I've resealed an aquarium with GE clear silicone I about three weeks ago. The surface is fully cured and the acetic acid smell is long gone, but where the silicone is thickest (especially around the bottom panel), I can still see some cloudiness underneath the cured top layer. Has anyone ever observed something similar? Should I be concerned or is the tank ready to use?
I'll do a test fill of course. I'm just wondering whether I should give it another week or two to cure some more. Though I really want to set up the tank now!
I would wait another week. Like you, I resealed my 300g and in the corners I put a thick bead. Waited a week, but silicone was still cloudy. I filled it and didnt have any issues, but after 2 more weeks under water, the silicone cured and became more clear. I also had an issue with yellowing of the GE1 around the edges in the tank and my sump. I freaked out a bit, but waited it out, leaving it alone. After a month or so, the yellowing went away. I didnt have any issues with fish during this time.
Glad to hear that your fish were unaffected.
Another week it is then. Better safe than sorry I suppose. The first tank I resealed I let cure for only a few days and after a few weeks I noticed a cloudy film had developed on the silicone. When scraped off it would come off in thick flakes. I couldn't find any conclusive info as to what it might be but I suspect it was algae. Seems like something in uncured silicone encourages their growth.
Another week it is then. Better safe than sorry I suppose. The first tank I resealed I let cure for only a few days and after a few weeks I noticed a cloudy film had developed on the silicone. When scraped off it would come off in thick flakes. I couldn't find any conclusive info as to what it might be but I suspect it was algae. Seems like something in uncured silicone encourages their growth.
Well that's the thing: silicones don't dry, they cure via chemical reaction. I've been looking it up and found that one-part silicones (i.e. the ones we use for aquariums) harden when exposed to ambient humidity. The best way of speeding up curing is by exposing the silicone to 95-100% humidity. As it cures it releases acetic acid which gives off that vinegar smell, hence when the silicone stops smelling we can usually assume that the curing process is complete.
So theretically if you reseal an aquarium and fill it right away the water will speed up the curing process but: (a) the water may work its way between the uncured silicone and the glass and compromise the adhesion between them; and (b) the acetic acid will have nowhere to go except into the water. That explains why when you finish resealing, if you don't wipe the silicone off your fingers and try to wash it off, it will come off in beads as it hardens.
So theretically if you reseal an aquarium and fill it right away the water will speed up the curing process but: (a) the water may work its way between the uncured silicone and the glass and compromise the adhesion between them; and (b) the acetic acid will have nowhere to go except into the water. That explains why when you finish resealing, if you don't wipe the silicone off your fingers and try to wash it off, it will come off in beads as it hardens.
