We are experiencing a strange problem and would appreciate it if somebody could offer any suggestions. This is our 6th year with a 24' round above ground pool and never had this problem before. It's like our pool is eating the chlorine as fast as we put it in. Upon startup we've shocked the pool at least 5 times now but the total and free chlorine levels are not budging must past 0. Water started out cloudy but with the application of algaecide, is now crystal clear and it's been that way for a couple of weeks. The last 2 shock attempts we've added 2 gallons of 12% liquid chlorine shock, and even that did not budge the levels. We are also running Chlorine tabs through a chlorinator. We've balanced out all other primary chemical readings which I will list below. The one thing I heard that could be causing this is a high phosphate level. We have not tested for that yet. But the pool location has not changed in 6 years and not sure why all of a sudden it would show a high phosphate level this year. We are in Massachusetts. Openings in previous years only took 1 shock treatment with 1 gallon of 12% liquid chlorine and we were fine after that. I am leary to just keep upping the chlorine shock levels because it's a waste and it hasn't worked yet and we are up to 2 gallons, my next step would be to dump in 3 or 4 gallons but I don't want to do that without exploring other options first. Perplexing to say the least.
Any suggestions would be appreciated.
(note: readings from 2 diff. water test systems offered via retail store; also have supplemented with latest readings via test strips)
Free Cholorine 0
Total Chlorine .4
Combine Chlorine .4
Total Alkalinity 120 ppm
Ph level 7.1
Calcium Harness 130 (currently adding in Calcium to bring up)
Cyanuric Acid 40
Total Dissolved Solids 0