Sorry this is a long story. I am trying to help out an old pre-katrina neighbor, and good friend of mine, with a pool disaster. The owner of the pool is an elderly lady who went to her local pool store ever since the pool was drained and filled about 10 years ago after hurricane katrina flooded the area with 6 feet of saltwater and about a foot of marsh mud on the ground and a few feet of mud in the pool. She really only keeps the pool for her neighbors grandkids to swim in and he asked me to take a look at it since he was going to take over the pool maintenance and he has never seen my pool green. Well she must have been dealing with the most incompetent pool store employee to have walked the face of the planet. The pool was totally green and the girl who did the water testing kept telling her that the water was testing fine so dump in a couple of pounds of shock and it should be good. When I tested this green pool the Chlorine was 43.5 and the CYA was WAY BELOW the 100 line on the TFT-100 cya tube so I took a pool store close to where I live now, which is pretty good as pool store go, and they told me the CYA was 175. As you might suspect they have been using tablets in an inline dispenser for the 10 years.
I had him change water till the CYA tested 80 on with the TFT-100. Shock level was 31 so I had him bring it up well in the 30ís and I lent him my test kit to do the shocking. I went over there and he had been maintaining a shock level of chlorine for several days and the pool was still green but just not as dark and getting a little bit of the cloudy or miky-ish look to it but make no mistake it was still green. The filter has only gained about 1psi. I did add some algaecide just because I had some laying around and as bad as things were looking, I figured what harm could it do.
Well here is where things get a little crazy. He told me the pool in this condition passed an overnight chlorine loss test! I had trouble believing it and was going to be around late that evening and the next morning so I did it myself and the pool had no loss of chlorine overnight and had less than .5 CC! After talking to him I realized either I forgot to tell him or he didnít remember, but either was the pool was not getting brushed at all. I know the not brushing could be a problem due to biofilm, but could that possibly explain the no chlorine loss overnight?
He stopped shocking over the weekend to deep clean the sand filter because he was thinking he might have a mechanical problem with the psi not rising. He told me on the outer edge of the filter, about half the distance from the outside of the filter to the stand tube was packed so tight he could hardly penetrate it with a dowel when he started. He cleaned it out good and put it back together. As it stood tonight the cl level had fallen all the way to 11 so we may be starting over tomorrow. I donít have all the test results in front of me but will get them tomorrow and post them but the other test numbers I didnít mention here looked pretty good.
So when he goes back to shocking or slamming whatever we call it these days, is there anything else you guys can see he needs to do? Is there any possibility, with the cya level so high for so long, and the pool being green for at least a month that I know of, that this pool has bred some sort of chlorine resistant algae? Should he try to maintain the chlorine level even higher than 31 he was doing for a week without a lot of progress? Could it hurt anything to raise it a lot more to try to knock it down?
About to the pool: