Do I need to SLAM? SWG issue?

[Jim H]

It seemed my chlorine levels were drifting down quicker than expected. I did an overnight test and the FC went from 5.5 to 4, the CC is <0.5.
My CYA is 70. Other numbers below and all look spot on.

I've had to run my SWG at 90%, 12 hours/day and even then I am supplementing in some liquid bleach.

I know it says to SLAM if FC drops over 1 overnight, which it did just barely... (1.5)

Or could it just be since it's been sunny lately (my pool gets sun exposure the whole day) that I need to up the hours I am using my SWG? I just thought that 12 hours at 90% was pretty high and to still not get chlorine maintained at that level...

Advice?

FC 4 PH 7.5 CC <0.5 TA 70 CYA 70 CH 300 Salt level 3500 (Manufacturer recommends at 3000-3500)

 

[duraleigh]

I just thought that 12 hours at 90% was pretty high and to still not get chlorine maintained at that level...

Of course that depends on the capacity of your SWG. Has it's performance been degraded?, etc.

I can say for sure that you should slam, regardless. A 1.5 ppm OCLT is excessive and needs your attention.

 

[needsajet]

The chlorine loss indicates slam, yes. Did you follow this procedure... OCLT Pool School - Perform the Overnight FC Loss Test (OCLT). It may be worthwhile doing it one more time to eliminate the possibility of testing error.

Is the pool sparkling clear? If not what does it look like?

Ignoring the copper and silver output for a moment, have you been able to find out the chlorine output of that unit in either pounds per day or grams per hour? There's a good possibility the SWG needs to run longer. I would turn it up to 100% in the meantime.

Have you tested the copper level recently? If it's high, there are special procedures due to staining risk. I'm not experienced in that, but experts would need those answers either way. I'm just curious, but is it possible to turn the copper/silver apparatus off?

Finally, I think it would be a good idea to keep your FC at or above 4 PPM as a plan develops. Use chlorinating liquid or bleach if need be, but don't take it up too fast.

You may have already done so, but if not, search the forum for "alternative sanitizers"

Trouble Free Pool Care (TFPC), as recommended here at TFP, does not include the use of copper and silver as sanitizers.

 

[mikemass]

Did you inspect your cell? Debris and/or scale on the plates can affect output performance. Most manufactures say to inspect and clean every 3 months.