Why would being up on foam cause a seam to fail? Seems strange that manufacturers would recommend it if it was detrimental. I've been using it under acrylic tanks for 20 years without problems, but maybe I've just gotten lucky. I'm about to setup a 180, and certainly don't want to use foam if I will regret it. Thanks for any info you have.
Foam is not a building material… it can crush over time causing tanks to shift. If your using it to compensate for a stand being un level it actually does nothing there also. Tank will still b un level, just on foam lol… basically ur creating an air gap underneath hundreds or thousands of pounds. That gap leaves room for the bottom seams to be un supported and push down/move. If the bottom seams cant push out, they cant fail when supported properly.
Acrylic and its bonding techniques are pretty darn strong… why alot of people dont see issues with small or new tanks. They can take alot of abuse. That doesn’t mean the practice of foam under acrylic is right or proper tho. Im not sure when people starting doing it. Its for plate bottom glass tanks and preventing pin point pressure breaking it.
Hate this example… but its a good one. The show “tanked” actually glued a sheet of ply directly to the bottom of the tanks they made. That went right on top of a metal stand. Shims were used between the ply and stand. Show may have been staged… but that chit was real
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Bigger the tank, bigger the problem up on foam. My personal experience was with a 450. It failed twice and was repaired before i realized what was happening. 3rd time it failed i took the foam out, repaired again and its been over 10yrs now.
