Catching a falling knife or SWG run time

[robdac]

I have recently replaced the SWCG in my way over-chlorinated (50+ ppm) new to me pool and fired the PB. Yesterday the FC was at 11 so I'm finally nearing the time where I'll be using the SWCG full time for chlorine. Problem is, I have no idea where to set it. The PB was using bleach because the old cell and controller were shot when we moved in. I understand that chlorination is a factor of SWCG percentage and SWCG/Pump runtime. Pump Runtime X %SWCG Opeation = Minutes of Chlorination

How does this plan sound?

The plan is to set it to 30% once FC drops to about 7 or 8 based on a FAS-DPD test and see what happens daily. Hopefully it will slowly drift to 5 or so and then I'll tweak it from there to maintain 5 based on the FC/CYA chart.

Thoughts?

 

[JasonLion]

Yep, that sounds good.

The normal way a SWG is adjusted is to watch the FC level. If it is too high turn the percentage down, if it is too low turn the percentage up. Generally you need to give it several days to settle after each adjustment, and it is best to measure the FC at the end of a sunny day to get reliable/repeatable results.

 

[Jabooh1]

I tried to set my pump run time first, based on keeping the pool clean and then adjusted the SWCG % to keep FC 3-5.

The pump should be more money to run than the SWCG so I have it at 6 hours and the SWCG at 60% or so.

 

[robdac]

I tried to set my pump run time first, based on keeping the pool clean and then adjusted the SWCG % to keep FC 3-5.

The pump should be more money to run than the SWCG so I have it at 6 hours and the SWCG at 60% or so.

When we moved in my two-speed pump ran on low 24/7 and on high several hours/day. I rewired it less than a week ago and I'm thrilled to be down to "only" 10 hours of runtime, with all of it on low. I'll probably be able to tweak it back from there a little too. I'm pretty amazed how little runtime is actually required for good water.