I am a building contractor and am about to build my own home(again) and want to do something different in the living room. My idea is to pour 8" thick re-bar reinforced walls 8' tall x 3' deep and 14' wide for a fish tank. I have access for 6' x 10' 2" thick acrylic for a viewing window in the front(sideways) if i have a 3" recessed key-way for it that should give a view-able area of 9'6" x 5'6". I have built my own concrete poured swimming pool and hot tub before so the concrete and plumbing does not scare me. The hot tub was out of the ground which gave me the idea. Also am putting a 10' x 3' acrylic viewing window in the pool but that another story. I am a beginner to this. Thinking out of the box, why could I not use a sand filter from a pool for filtration and a pump. Thinking of going fresh water for ease. What do I need to accommodate for or think about?