Hello new to the forum, pool owner for 3 years never had any problems. 23,000 gallon concrete pool with D.E Filter. Pool is almost 20 years old. All chemicals are at ideal levels via strips and 3 pool store test readings except free chlorine and total chlorine reading 0. Pool water is crystal clear and no one has been in yet this season. I've been shocking with calcium hypochlor and maintaining chlorine tabs with stab in skimmer. I do get some alage buildup on walls. I shocked with 3lbs of calcium hypochlor and added 2 tabs today and tested with a strip half hour late and got good readings. An hour after that same great reading but no FC!

I have a Taylor 2006 on the way.

My latest reading from leslies compares to 2 other stores and strips

FC 0
TC 0
PH 7.6
Total Alk 120
CYA 30
Calc Hardness 160
TDS 500
Phosphates 300ppm I added pool perfect with phos free
Nitrates 2ppm

Please help this is driving me crazy. Never had a problem holding FC.

Is a partial drain and refill in order?

Thanks

Mark