Resealing Silicone????

[gmatt]

I have just removed my overflows to put in a calfo type overflow on the top of my tank.

My problem is I thought I would be able to remove the overflow without cutting into the tank seal of silicone at the bottom of the tank. Well the short of it is I had to cut into the silicone bead at the bottom of the tank. Probably 1/2".

My question is this I've heard New silicone won't stick to old silicone. Is that Absolut, of mostly true?

Is is possible to put a large patch of new silicone? Say instead of 1/2in. maybe 2in. by 6in. ? Will it hold water? the tank is 24" tall (water pressure issues?).

I hope I don't have to cut out all the silicone in the whole tank and reseal everthing.

Thanks in advance for any help.

[OnTheReef]

Putting new silcone on top of old silicon is certainly possibly, the trouble is getting the edges of the new silicone to seal completely. If sea water can get in between the new and old silicone, the new silicone may peel off over time. I have repaired leaks in the past by cutting the skin off the old silicon, rubbing it down with denatured isopropyl alcohol to get the old silicon tacky, then apply fresh silicon on top. The trick here is to get the new silicone ONLY on the tacky part of the old silicone, so that no peeling edges develop.

Good luck!

OnTheReef

[gmatt]

<a href=showthread.php?s=&postid=6944490#post6944490 target=_blank>Originally posted</a> by OnTheReef
Putting new silcone on top of old silicon is certainly possibly, the trouble is getting the edges of the new silicone to seal completely. If sea water can get in between the new and old silicone, the new silicone may peel off over time. I have repaired leaks in the past by cutting the skin off the old silicon, rubbing it down with denatured isopropyl alcohol to get the old silicon tacky, then apply fresh silicon on top. The trick here is to get the new silicone ONLY on the tacky part of the old silicone, so that no peeling edges develop.

Good luck!

OnTheReef

Thanks.