Might be a stupid question but it has been bugging me

[StirCrazy]

hey I have been reading both sides of the coin on weather pt put your LR on the sand , on the bottom of the tank, or on a rack of some sort. while everyone has there opinions there is no definat reason to why one is better than the other.. after thinking about this something struck me funny about 2 of the methods.

a glass fish tank is suported by the outside edges only that i why you can buy stands that are just frames.. now how much weight can you put in the middle of the tank befor the bottoms fails. to me if the weight is spread eavenly (as in a sand bed) you shoulden't have any problems. now when we are talking about live rock you are putting wight in spicific points. ie, the part of the rock that touches the glass, so if you pile it up you could have a pinpoint weight of 30lbs more or less depending on the shape of the rock. now if we build a rack like some people have said using 1" pcv as the legs we are now suporting the entire rock load on legs.. I saw one that holds 150lbs and only had 6 1" legs so at ~25lbs for each leg I would guess that is a significant spot load on the tank bottom.

now the other method I saw was to place it directly on the sand and when I thought of this.. ya that is probably the safest way to do it as the sand bed will spread the weight of the rock over a much larger area than the foot print of the rock its self. sand will distrbuite a load over a angle of aproximatly 45% so 150lbs of rock that covers a area of 18" X 40" would have a weight distrubation area of aproximatly
26"X 48" which would make a weight of .1 of a lb / square inch or 17lbs / square foot.

Steve