We have an in ground pool that we usually have professionals come open and close. This year we tried to open it ourselves, at first all was going well (water was clear). Then after we put together the pump/filter noticed there was very little pressure going out the valves in the pool. My brother replaced the air pressure gage thinking that would fix it, but it is still not working. We have the two valved in the pool, one is extremely weak and the other really does not seem to be working at all. We tried to backwash it, but it still won't work.