Target FC for SWG pool in winter when cell not on as much

[IsaacFL]

In the summer, my pool is in full sun, and my cell is normally set at about 35%. Now that the fall is here and the sun has shifted, my pool is in full shade all day due to a wall immediately south of the pool. Now I am running the cell at 5%.

My CYA is at 70, so my target FC for an SWG is 5.

My question is, now that I am barely running the cell, should I use the target FC for a Non-SWG pool which at CYA 70, would be 8?

 

[Jezza]

If you are still using the SWG for your chlorine and it is maintaining your target FC for your CYA then why change? If it gets to the point where your reducing your SWG down to a very low point can you reduce your run time for the pump?

 

[IsaacFL]

I was just getting ready to lower the run time, when I started to wonder about my original question.

My normal target is FC at 5. But with a non-SWG the minimum FC is 5, with target at 8 for a CYA at 70.

I was concerned that algae may be able to get started with the minimal run time, since I could have FC drop to 4 and still be in range for my SWG. But 4 would be below minimum for Non-SWG.

I guess if my real question is, if I turn off the salt water cell, do I treat it as a Non-SWG pool for target numbers? And how much difference is 5% vs 0%.

My CYA remains at 70 either way.

 

[chem geek]

Yes, I would treat the pool as a non-SWG and use the higher target. This not only accounts for the lack of consistent dosing, but also for how the active chlorine level is lower in pools with CYA as the water gets colder. Algae growth also slows, but to ensure opening the pool in the spring without algae, it would be best to keep the FC level at the non-SWG level. If you use a pool cover and with the sun at a lower angle and the lower water temperature you should be using a lot less chlorine so it should be pretty easy to maintain.

 

[IsaacFL]

Thanks. I am going to put some bleach in to take it up to FC 8.