20,000 gallon in-ground vinyl pool
Hayward 1hp, sand filter
Auto chlorinator which holds 10 tablets
We run the filter from 6:30 am - 7:00 pm DAILY
I have read your sticky, "Turning Your Green Swamp Back into a Sparkling Oasis".
I'll give some background first. We had algae and fought it for a little over a month. We finally made some corrections to the pump system, like replacing a seal which made the pump work better, then we replace the sand in our Hayward. Once these 2 things were done, we shocked the heck out of the pool and also added Green Treat. We ran the pump 24/7 till the algae was all dead. We added Flocc, ran the pump on re-circulate for 2 hours and shut it off till the next morning. We vacuumed to waste a couple of times and backwashed. BAMMMMM....Crystal clear water, FINALLY. It stayed like this for about 2-3 weeks. It was wonderful. We took a sample in to our local pool store and was told the stabilizer was getting low. Back to the grocery store we went for panty hose. We added the chemical to the pany hose and milked, and milked. But the water stayed crystal clear.
This past weekend, we swam for 2 days straight with friends in about 85-87 degree weather (southeast Texas) and the water being about 80ish. This is what our weather has been for several weeks. We needed to add some water this past Sunday so we did, then it poured Monday. NOW I have algae again.
We took a sample into our local pool store and the readings were as follows:
Free Chlorine: OVR 10. ppm
Total Chlorine: OVR 10. ppm
Combined Chlorine: 0.0 ppm
Hardness: 160 ppm
Alkalinity: 40 ppm
Cyanuric Acid: 70 ppm
Copper: 0 ppm
Iron: 0 ppm
Total Dissolved Solids: Not Run
We were told to scrub pool, and sprinkle the Green Treat and run filter 24/7 and then sweep to waste then backwash
OK, here is my question. Why is my pool getting algae when my chlorine is OFF the charts?