Advice? Silicone recommendations

If it was exterior silicone, dunno...

This is a widely discussed issue, it comes up over and over again. The bottom line is the best one, which almost all aquarium manufacturers use, is Momentive RTV 100 series.

https://www.momentive.com/products/show-technical-datasheet.aspx?id=10289

For clear, this is RTV-108. You can get this in many places. I guarantee you this brand is safe, there is zero question. Also it's not particularly expensive

72 hours to water-test. 2 weeks to full cure / reef safe. Yes, 2 weeks.

I'm not the expert on full assembly but what I do know is that it's one thing to just reseal the inner joints - a full assembly is a whole 'nother level.

Getting a joint with no bubbles that could push through existing panel-to-panel joints, you got me there....I tried 2x on one tank and didn't even bother to water test it.

 

Also surfaces have to be super clean, scraped down and wiped with denatured alcohol prior to application but I'm guessing that you knew that. As for it coming off easy, silicone is kind of like that in the way that once you get a corner/edge going, you can peel it off as it has good self-adhesion (forms a solid that doesn't tend to tear) but the adhesion to the glass is a bit different mechanically, you can peel it off but if you try to break the bond by sliding the glass panel (if you could) it would not detach easily. Hard to explain but the point is that ripping the silicone off being easy does not necessarily equate to a bad application/bond

 

Either the stuff Bud mentioned or anything listed and sold specifically for aquariums. When I needed some I bought aqueon labeled silicone. Probably paid a little more, but it ensured that is was the right stuff that wouldn't cause issues.

 

That cure time is for all silicone. No matter what you have ever heard, silicone has a 2 week full cure time to reef safe. Others can say they didn't wait that long and were fine and so might you, but you also might not.

i.e. siliconing up a sump quick and putting it into action in an established tank could lead to issues that you might otherwise think were something completely different if you thought 72 hrs was full cure reef safe time. This 2 week cure time comes from manufacturers of aquariums.

 

I pulled the acrylic off the bottom of that 120 I bought from you and there was silicone under there was still actually 100% uncured. Still smelled and felt like it had just came out of the tube. I'm guessing whoever tried to reseal that tank, and stuck that acrylic on the bottom didn't let it cure out well enough before filling it back up with water.