How to do new Silicone

I've done it before, but never with a lot of luck. Basically you remove the old silicon with a razor blade, then put the new silicon in there. I never had a whole lot of luck because the tank would end up leaking later anyway.
 
I've never done it but have a older used 150 I am thinking about resealing if I decide to use it. I hear that for one thing you need to remove all old silicone, new will not bond to old. And once removed the glass needs cleaned very well. Also, and depending upon the size of the tank, you may need to wait several weeks for it to cure properly.
 
All good opinions and advice. So far I've been scraping with a razor blade. I'm finding that the glass still retains a teeeeeny tiny residue. I haven't done further cleaning with vinegar as recommended in the article I read. Maybe that will remove the residue....we'll see. I'm wondering if this tiny tiny amount will hinder the new from bonding. You can't even feel it with your hand and the blade skims right over as if it wasn't there -- very slight 'stain' sort of. Again...I guess we'll see.

One other thing -- just a thought about how tanks are constructed in the first place ...as I'm scraping with the blade I find myself wondering -- what is holding the whole thing together? It can't be the silicone holding it....that wouldn't make sense -- so what "welds" the pieces of glass together? Then my further thought, is there a risk of digging into the seam with my razor blade too deeply and weakening whatever is gluing the glass together?

It's nice to have folks on the forum looking over my shoulder as I do this. Thanks folks.
 
...what is holding the whole thing together? It can't be the silicone holding it....that wouldn't make sense -- so what "welds" the pieces of glass together?

It better make sense because thats it...

An acrylic tank will have a glue that welds the acrylic together but on a glass tank its just glass and silicone. Some do seperate all the panes when they reseal.
 
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