Sealing A Leaky 55 gallon

It helps to lay down strips of tape about 1/4" from the corner where the ege of the silicone will be. This helps to keep it clean and professional looking. Just make sure you clean it all out real good, definitely use a couple new razors. I would switch them out for new clean razors frequently since razors are so cheap.

 

+1  Follow these tips and you will have great results.  It's amazing how much of a difference a new blade makes in getting that final little bit of silicone off.  I also use a silicone tool available at most home improvement stores.  It's like a corner squeegee that puts a nice rounded edge on the silicone.  I can't get a good edge without it and it makes for professional looking results.  Look here at my sump build for some examples  http://www.greateriowareefsociety.o...fault.aspx.  About cleaning with alcohol, I always just used a clean washcloth and a little water, but if you let the alcohol dry/evaporate, I'm sure it would be fine for using in your tank.
--AJ

 

I read a post on RC the other day. It said if your tank leaks from the bottom then you have a major problem, and that stripping out and resealing the silicone seals will not fix it...If it leaks from the bottom than the silicone between the glass back and the bottom, the stuff that 'glues' the two panels together, is screwed* and you have to actually take the tank apart and clean all the silicon and glue it all back together, then seal the seams.

I could be wrong on this.
*adjusted for language by AJ

 

You're right in the sense that it is the silicone between the glass that does the majority of the work holding things together.  I think you have to evaluate things on an individual basis.  If you know the history of the tank and maybe you just got a razor too close or something, I would have no hesitation fixing it and using it with confidence.  Now if it's an old tank that you got used, have no idea of the age, the rest of the silicone is in crappy condition, then that's a different story.  It's a judgment call.
--AJ

 

That's good to hear. I am living in denial that my tank leaks. I know it leaks. I know where it leaks. The problem is it only leaks a little bit....the water evaporates before it has a chance to do any damage to the stand, floor, etc. It drives me crazy. Sometimes it doesn't leak for weeks. I guess I will try to fix it one of these days.

 

I have a glass cages tank too...I hope mine doesn't leak!  I've not noticed anything.  As well as they build those things with thick glass, lots of reinforcing and lots of silicone, you have to wonder how they could leak. 
--AJ

 

I'm not really blaming glass cages.

Tanks leak. Fact of life, I think.