did you check the link I gave you above? yes you can do that the link should describe how but it won't be as easy as the rocks. youl have to decide for yourself how your gonna cure it. you might be able to get by via fillling the tank up with water and doing very large (100%) water changes until the ph of the water in the tank matches the ph of your tap water. then refill the tank with water and everything else you want/need for your fish.
But I was thinking about the joint at the bottom and the wall. They will have the 30,000 lbs of force on them. What you did was per sq inch I think. I don’t remember all that math from calculus.
Yes, there's 30,000 lbs of force a la gravity exerting its pull on the mass of water. Joephys is getting to net force on each wall, and he had to use calculus because pressure varies with depth (using the same methodology, he can get the force exerted by a column of air [or any other fluid, for that matter] against a wall of a given height). The joint at the bottom of the wall will be subject to a certain amount of pressure which will remain constant no matter the length of the joint in question (assuming depth is held constant). Pressure is a more useful thing to think about if we're concerned about the bottom of each wall being pushed away from the slab.
Almost 9,000 lbs. lateral net force on an 8-foot wall? Wow, Joephys! A friend of mine just fixed a submerged concrete wall that bowed out and broke; now I understand how it happened!
For filteration, a pool filter won't give you any bio-filteration (Pools use chlorine for that). Also, a filter outlet that low in the tank might be problematic because the water pressure might be too great. This weakness could just about empty your tank.