Hi there, We are in our first season of owning a pool and are having some trouble already. We had about a week worth of algae bloom and have treated with algaecide and 10 gallons of shock on Friday. It turned the water teal and cloudy and we took water to the pool store yesterday where they found that the chlorine level was very low (less than 1 ppm). We treated with 20 lbs of Bicarb to increase the alkalnity (which was low) and then two bottles of yellow rid (after 6 hours and vaccuuming) and another 10 gallons of shock yesterday evening at the recommendation of the pool company. This morning the chlorine and free chlorine levels are off the high reading of the strip and the alkalinity is in normal range. The pH is 9 though. Our pool is 20 x 40 and the pool company estimated it is probably 35,000 gallons or so. We have a sand filter which is about 20 years old and the psi reading when clean is 15. We have run the pump/filter continuously since Friday and the water is still quite cloudy (so much so that we can't see deeper than 2 feet or so). We have vacuumed to waste, vacuumed through the filter, backwashed the filter etc. Before the algae bloom came, the water was clear on opening and only had a little sediment on the bottom. We delayed adding chemicals because we found that we had a liner leak and were trying to get the liner replaced but then found out the liner we wanted wasn't available until mid June. That's when we decided to try to clear up the pool. Sometimes after vacuuming there is brown water returning to the pool. It seems to us that maybe this is a filter issue? Shouldn't the water started to clear by now with all the chlorine levels as high as they are? Should we be asking someone to come look at our filter (a 20 year old sand Hayward filter), should we be looking to upgrade to a DE filter? Should we be thinking about using a flocking agent? I know people seem split about the use of those with some people saying they can cause problems, etc. Should we be giving the pool more time to clear? Maybe we are jus impatient? I would love to hear anyone's thoughts on this issue. We are entirely inexperienced with pool stuff and would very much appreciate the advice of anyone who has time to weigh in. Thank you and enjoy the weekend.