So this is my first year with a pool - we built it last summer and only had it open about 2 months last summer so this was my first full summer. I found TFP while we were building and I spent quite a bit of time reading up on chemistry management and thought I had a good handle on what to do. I bought a TF100 test kit and have been religious about testing and maintaining the water chemistry.
Opened this spring in early April. It took me about a month to get all the chemicals where I wanted them. About the end of May I saw just a little algae on the bottom and thought I should SLAM it. This was my first time through a SLAM and I am not sure I did it exactly right, but it went away and all looked good. It took about 10 days to complete.
Pool was only clear for a little over 2 weeks and the algae was back again. SLAMed one more time. This time I removed light niches, ladder and return nozzles to make sure everything was clean. Again - about 10 or 11 days to complete SLAM and had it all back clear again for July 4th.
This time it stayed good for almost 6 weeks til mid August. I checked clorine every couple of days and it never dropped below 5, but again the algae came back. The water was still fairly clear but there was just a dusting of green in spots across the bottom. So lets SLAM again. By now I am pretty sure I am following the directions exactly. CYA was 65 and so I raised CL to 26 and held it between 25 and 30 for 2 full weeks. Was all good again by around 27th of August and so swimming once again.
Last week i see a small spot once again!! I am at wits end so I break down and consult the pool builder. These guys also do pool maintenance for a number of large pools so I hope they have some idea that can help. They tested the water and told me the salt was low (it was at 3000 as I had been backwashing and replacing water), but everything else looked ok. They thought it might be high phosphates and said they would come by and test it and have a look at the equip to make sure its all good. Long story short they said everything looked fine but that the CYA was 80 and that could interfere with cl ability to kill algae. When I tested with TF100, I consistently got 55, and he was using same type of reagent, but he got a very different result. When he came by, the algae patch I had seen appeared to be gone, so he said watch and see how it goes. He suggested running the pump longer (I only run it about 14 hours a day when not SLAMing), but said everything looked fine. Of course I look at the pool 36 hours later and I can see algae growing over about 10% of the pool bottom. I am going to let it go for a few days to get worse before I call him back, but this is really crazy!
So in general, I have been targeting:
At this moment, I have:
CYA 55 (by my measurement - is there a more accurate test I can find?)
I run the pump 14 hrs/day at 2000 rpm so I should be getting plenty of circulation.
Any thoughts? Its a nice looking pool, but I'm about ready to throw in the towel...