Heres my story. Having to build the pool myself as there is no qualified pool builder in the philippines where I am building this. There is an on property water tower to fill the pool. I have had no luck finding a one line diagram that answers my questions. Please review this one line diagram to see if Im all wet (pun intended). At the bottom near valve J, its says "To Waste" which got cut off. So in normal operation, valves A,D,N,L,J, are closed, the rest are open. In backwashing the Sand Filter, valves N,L,H, I , J are open, the rest are closed. In filling the pool, N, L, G, D, A are open, the rest are closed (fills thru main drain, or could route to pool supply 1 & 2 instead). To drain the pool, A, M, K, J are open, the rest are closed. Please let me know your thoughts, or if I am missing something. All input appreciated !