Hit the 4 month mark on my chlorine based spa after conversion from Baquacil - using the methods from TFP with great success. I was having only a 20-25% over night FC loss at 98-100F, great water clarity, no foaming. Decided to go ahead and change the water in spite of it being in great condition b/c I had the time, needed to replace the weir and now have some Ahh-some. Did 2 treatments with minimal, then almost no gunk on the second round. Finished out by emptying, wiping down, rinsing, emptying as much as possible, then refilling.
After adding my calcium, baking soda, leftover Gentle Spa and muriatic acid per PM, then finally bleach I have the following:
CH is 140
FC 10.5 and CC 0
CYA was added to attain 30, but I won't test the level for another 10-14 days.
I'm also going to wait on retesting the Borate for a few days before making any further adjustments.
1: do I have to SLAM now? If I understood some earlier threads, SLAMing doesn't hold for spas.....should I just see if I'm 20-25% or less in my over night FC loss and call it good?
2: did I need to shock after the refill... I shocked cause I thought it was what I was supposed to do, but now what? Could I have just added enough bleach to get to 5-6 and stopped there? instead of the shock level of 10 (assume zero dissolved CYA)? I haven't been shocking at all the last 4 months......just using maintenance 3.5oz 8.25% bleach per 1 person hr, dropping the temp when OOT, and testing and using PM when needed.
Water is sparkly beautiful!