<a href=showthread.php?s=&postid=10066984#post10066984 target=_blank>Originally posted</a> by Mr31415
jacmyoung - yes and no. Three layers of 10mm siliconed together but the silicone does not fill the whole area - it is mostly on the lines where the panels are joined. The silicone strips are about 6" wide...
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I can only speculate since I am no expert on this, but having silicone only on the perimeters would leave uneven stress especially close to the strips on the inside edge because silicone has thickness, even though that thickness is very small. That seems to explain the location of the crack, it not only is at where the holes are, but also close to the silicon strips so the stress (unevenness) is the greatest. Towards center away from the strips the glass should have deformed enough to be in full contact and in even support.
But since this is a common practice in your area, did you ask around what experience others have with their large tanks?