In regard to the question of foam or no foam. I did speak with the MFG, who in this case is Miracles. They do recommend using it, however, if you really feel that you have a smooth flat surface then go ahead and omit it. It's really just an extra piece of insurance. When posed the question in regard to using it with a tank that has base trim, they agree don't do it. The reason being you will have too much compression of the foam just around the perimeter that may cause the tank become unbalanced. For example, my tank has a base that is 96" x 24", or 2,304sq in. Assuming about 500lbs for the glass and 2,500lbs for the water, thats 3,000lbs spread over 2,304sq inches yielding only about 1.3 psi on the foam. Basically nothing. Same tank with a 1/2" perimeter trim you get about 12.5psi since the load is now only spread over about 240sq inches. This will definally cause the foam to compress some distance and possbily unevenly. My tank does have some minor trim but it is only 1/16" thick which is neligable.
Having said all that, I'm still going to replace the foam. But asking for more specific recomendations from them. I'll be using a 5/8" "open cell" type foam. This is usually recognized by the standard inexpensive white sheet comprised of what looks like little 1/8" round beads stuck together. Also it is what lrac2006 suggested and pointed out as my "packing foam sheets" in a recent post.
Now just to figure out how to lift it up again and swap foam?
Thanks,
Jon..............