Rick here. I'm new to the site but have been taking care of our pool for 19 years. We have a 23,500 gallon plaster pool in Bethlehem, PA. Hayward 1.5 HP single stage pump, Hayward DE Filter, Polaris Pool Cleaner. My wife pretty much did the chemical thing until about 4 years ago (I just did the heavy stuff). I then took over the whole deal and got water tested at Leslie's and an independent store. Sometimes went to 3 stores, got 3 different results and wondered which (if any) was correct. Willow Park Pools has a computer test program ... WaterLink DataMate 10, but it seems inaccurate as well.
We are looking to replaster (or Diamond Brite) so I thought I'd test myself and save the above hassle. I bought a TF-100 Kit and have been using it for a few days. We've put the replaster off until next year, but I am getting ready to close and have some questions. I see the advice to wait until water is below 60 degrees, and open before it gets above 60 degrees ... and it certainly makes sense. We normally close later September and open later May (8 months closed!) ... water temp above 60 in both instances ... "knock on wood" we've never had any algae problems ... water always clear... so far anyway We've always used the 3" Trichlor pucks which I've stopped doing per this site. Started using 8% bleach now.
We normally shock before closing (Dichlor Shock) and add polyquat algaecide. With my high CYA, I want to know how high to shock and how low to let it drop before closing?
My numbers per the TF-100:
Free Chlorine 8 (per this site I've started adjusting it up to around 10)
Combined Chlorine 0.5
My water is very clear ... no problems we can see ... we get lots of sun daily. Per the CYA/Chlorine chart on this site, free chlorine should be 7 min, 12 target, and 39 shock. I realize that 39 is too high to boost it, so I wonder how high to raise it before closing? I calculated the boost that the shock we usually used (dichlor) raised the free chlorine, and I figure it gave a boost of around 8.
Also, how low to let it drop before closing ... realizing high chlorine is hard on the pool cover and can render algaecide ineffective?
Thanks much for all of the info on this site, and for any help with the above.