I would defiantely wait to hear from more knowledgeable people than myself
before attempting to wedge a tank that is full.

Perhaps acrylic is different than glass but you definately need to have the
tank level.

I just lost a 75g that was 7 years old about 2 months ago and still cant
figure out why.

Other than that problem that even the Mfg could not explain, I have never
had any problems with my tanks and I have never EVER used any type of
padding. I currently have 12 tanks running including 2 180gal and there is
no padding under them what so ever.

My advice may seem drastic but I suggest you take the tank down, lose the
padding, and make SURE your surface is level. To be honest I am not exactly
sure what a knee wall is but if it is what I think it is, I wouldn't try
putting a 55g on there unless I knew it was reinforced VERY well.

Main thing is, make sure the wall is still level. If not, I recommend you
find a new home for that 55g =)

HTH

~Mort

"Mark Breithaupt" wrote in message
...
We recently set-up our 55 gal. acrylic w/ 70 #'s LR.
We placed a 5/8 piece of polystyrene, cut to the dimensions of the tank,
underneath to distribute the weight. Our knee wall top has a slight bow
(about 1/16-1/8") from end to end of tank.
Problem is one corner of the tank rest slightly above the pad. You can
slide
a sheet of paper underneath about 6-8" square and deep under one corner.
There is no noticeable compression of the pad, but you can feel a little
tighter pressure into the side of the pad in the center. There is slightly
noticeable difference in the waterline space (waterline to top of tank) on
the end with the space between pad and tank.
Question:

Can our tank tolerate the strain in areas where the P'styrene is not
adequately compressing or making contact with the tank? How strong is the
tank for unbalanced seating?

I will be inserting a long wide wedge into the space today to try to
equalize the support on the low side, but other areas of inconsistent
support may still exist.

Any suggestions?