Definitely not the same spot as it was a couple seals back. All of that seal is gone and with it went the problem.
Truth be told I can't tell where the leak is coming from but wherever it is, it's on the opposite side of the tank this time and again appears to be low.
Current status:
Tank is drained, dry, stripped of the silicone bead and there's a big fan roaring inside. I'll have it spotless within a couple three days and my plan is to have another bead laid soon.
A couple of things I've noticed that I wasn't expecting:
- The silicone makes a crunchy sound when being stripped from the glass. Sort of like it might sound if there had been sand embedded in the bead.
- There still was a tiny bit of uncured material in one corner, and
- The silicone bead came apart in shear. Normally I expect a bead to seem a bit like a rubber band but not all of this was like that and in a couple spots it would easily separate from itself. I saved a sample and will upload a pic of it tomorrow.
Thank you. I've heard you and John refer to that seam between panes as a structural seam. I've always thought of it as a cushion and nothing more. I've seen videos of large tanks being built and it never has seemed to me like there was any particular voodoo associated w/ that seam and that it was unlikely to be more than the cushion I thought of it as. I am eager to understand this better. Please tell me more.
At this point I would really like to see this thing up close before saying anything for certain. But if you found uncured silicone that's another issue, you simply didn't wait long enough or that bead is just too fat.
The silicone between the glass panels, what I call the structural seams, idk what actual term is, are what hold the tank together. The silicone only has strength right where its contacting glass to glass. The "seals" only waterproof the tank, do very little in actually holding the tank together.
Usually the structural silicone will be effective for the shelf life of the silicone--a long ass time. Whereas the seals, constantly submerged and exposed to varying degrees of salinity and light, degrade much faster. BUT if the glass panes are constantly being stretched apart, even a little bit, the structural seams will be compromised much faster than normal. This is what I think happened to your tank, but like I said Id really have to see the thing up close.
You mentioned no concentrated load earlier in the thread and you are correct, but that is not the issue. The middle-bottom seam of your 10' long tank is the weakest part of the tank simply because it is farthest away from the sides of the tank, where the bottom panel is also supported by the structural seam on the side panel. It's at this point I have more questions than answers, Is it just a single pane of 3/4" glass on the bottom? How is the bottom area of the tank constructed? Is the bottom panel indeed "floating", elevated off the stand and resting on the inner channel of that trim?
This games not over, I think you have to expand your playbook though. One option is a bottom eurobrace, or maybe just some thick strips of glass to reinforce the bottom seam in the middle. One caveat there is that a bottom eurobrace will be next to impossible to remove if it leaks again.
If you try another reseal, find some way to brace up both the bottom panel from underneath and the long side panels in the middle from outside BEFORE you fill test it. This could be bar clamps or heavy duty straps or some kind of DIY lumber jig bolted onto the stand. The point is, if it doesn't leak when braced up, we'll know a lot more about the problem if it leaks again when the braces come off
...and smooth out those seals, they should be much thinner imo, more of a concave cross section than triangular.
wednesday13
. No tape and she'll be a fatty for sure. Might just fill that dude up w/ a little puddle in the middle!
