I've had a pool for about 8 years. It's a sand filter intex 18'×52". This year due to life getting in the way I just started trying to get my pool going for the last week. I started with half the pool filled with last year's water and filled the rest with fresh. As of right now my water is cloudy and I can't seem to keep chlorine in it. I have used lots of algaecide and 4 gals of shock to start. (POOL store shock) from there I have treated for metals, went from high ph to low, increased alkalinity, added lots of clarifier, 4 more bottles of shock-2 at a time and opened my tablet dispenser to more than what it should need. I don't have the test kit going to buy one after posting this. I only have the strips. I have had to back wash my pool almost 4-5 times a day because stopped giving good flow. I netted and vacuumed what i think is most out of bottom. I want to add sparkle up by bio guard but without going to POOL store i don't know how much to add and last time they have me advice on it I had to backwash the pump to death. The instructions go by samd filter dia and i don't know how to gauge that. I'm at a loss about to drain the water and start over. I know this is very long story. Right now no free chlorine low ph, total alkaline about 180, and 0 cya please any help on how to figure out dia of pump and suggestions on where to go with this I would so appreciate!!!