first time i have attempted something like this but i am sure it will hold up. its outside dimensions are 8'x4'x4'. inside its 87"x39" and will be filled 40" high making it 587 gallons. plus little more by the time i build the sump and add its size. it has a 2'x3' viewing window in front and an 8" high 12" wide step on the front and alond both sides to be able to easier vew from the top. its r-30 insulated in the walls and floors to help keep water temps more consistent and deaden noise, or at least thats the thought behind the idea.lol im gonna go with using a pond liner for water tightness to reduce cost and just because i want to. lol. im going around the top with 1"x8" boards to make it cleaner looking and under the overhanging lip inside im going with the lighting to give it a nice clean look so i dont have to hang lights above the tank. will have a removable sheet of plexiglass cut to lay on top to also help keep heat in in winter and dirt out. thanks to mfk member ideas i am also putting in the drip water changing system to do constant automatic water changes. not sure what im stocking it with yet for sure. looking at going with 3 rays, some clown loaches, black ghost knife, and some bala sharks maybe?? i dunno yet, got time to plan that out still. anyways, here are some pics to see how its coming along.