Chlorine loss problem

[mgtfp]

During the day SWG at 100% for 13 hours. Thursday night FC at 6.5ppm. Added liquid chlorine to boost to 10ppm. Also did acid bath of cell as noticed some sediment (possibly due to high TA) and added 400gm of pH up to get to 7.4 pH.

There's no need to push pH from 7.0 to 7.4, it'll just push up your TA unnecessarily. Also looks like that last test was from a store - pH is probably one of the least reliable store tests from my experience. Only do corrections based on your own testing.

As mentioned by Mdragger88, avoid descaling the cell with muriatic acid even though that's what the manufacturer recommends.Each time you do that, a layer of the cell's rare earth coating gets removed.

But I still had CYA loss of >15ppm in the pool over 3 days with the cover on the whole time. Sample removed in the pool did not have the same loss.

I don't see another explanations for this other than dilution in the pool sample.

Make sure you track other parameters like salt and CH with your own testing to see if there is a correlation to the CYA loss. What is the CH of your fill water?

 

[Karlosw]

If you’re mixing pool store cya tests (& others) with your own they undoubtedly will be different & all over the place.
Stick with your own results for comparisons.
Is your cya reagent old? It’s quite robust but it does get old especially if exposed to light or temp fluctuations. When I got my last new bottle I realized my old stuff was yielding lower results.
Some folks in the US have reported experiences of less potent cya also. You may want to try a different brand. Not sure what the weather is like there but in the height of swim season you should aim for around 70ppm cya. May want to aim for 50 initially & do another
Overnight Chlorine Loss Test to be safe before raising to 70.
If you’re putting the sock in the skimmer & then backwashing within a week you may be losing some of your cya. Try hanging the sock infront of a return so it is distributed into the bulk of the pool water immediately & none is trapped in the filter.
Btw- cleaning your cell with acid reduces its life. Try to gently use a credit card or popsicle stick before resorting to vinegar or next diluted acid.
Keeping csi in line (slightly negative)should help prevent scaling so the cell doesn’t require cleaning - turn on csi tracking in poolmath.
What is your water temp?
You can point your jets up & run any water features to increase ph without increasing ta.

The pool shop test reinforced my home test. Normally just rely on home test, but due to the change in CYA I did a pool shop test to confirm.

CYA is 1-2 months old.

With the CYA, I did aim for 70, but as per earlier post, I added 2kg of CYA when levels were 40ppm only to end up back at ~40ppm after a week. Not that I have added ~9kg of CYA only to end up with levels not being <30ppm (the min level of my test kit).

Thanks for advice on sock placement, cell washing and CSI monitoring. Will try each of those.

Water temp is 28-30 degrees (I have solar heater).

 

[Karlosw]

Please report your findings, especially chlorine loss, after you give the Bio-Klenz a week or so to begin it's mission. Please note that your cell plates in the SWG will get a nice cleaning as the Bio-Klenz passes through the cell. Be sure to super chlorinate when yiu add the appropriate amount of Bio-Klenz. The Bio-Klenz will loosen bio-gunk from your plumbing that will cause yiur free chlorine to go down as it ozides the planktonic biofilm.

Will do. Thanks.

 

[Mdragger88]

Water temp is 28-30 degrees (I have solar heater)

The warmer the water temp the faster cya depletes. That may have a little to do with it but really doesn’t account for all of it. 24 hours after you added did you test & confirm the expected rise? I can’t help but think either there’s a bad batch of cya involved , the pool volume is larger than you think, perhaps there’s a reagent issue or maybe a combo of all these factors. The solution there is to change the possible variables one at a time to eliminate them.
If there’s some funky stuff in the pool that’s eating your fc & cya then the answer is to thoroughly repeat the
SLAM Process - its very possible that your last one ended prematurely. That would be the 1st step before resorting to any additional products.