CYA level in pool

Hi John, thanks for updating me on that, when needed I will order refills etc. through your good self. Cheers, Paul

Hello again John
Having just arrived here at Villetoureix for a couple of weeks between bookings, I have done a couple of pool tests, and would really appreciate your thoughts on the results?
Tests carried out with COLOR Q equipment to laboratory standards!!!
20/06/18: Free Chlor; 9.45 - Total Chlor; High - PH; 7.1 - Alkaline; 42 - Calcium; 58 - CYA; High
24/06/18: FC; 9.15 TC; 9.15 PH; 6.5 AL; 32 CH; 32 CYA: High

If CYA is too high, shouldn’t Free Chlor read a lot lower than Total Chlor?
Should I do anything about the low Alkaline and Calcium hardness?
I am in the process now of evacuating a Litre or 2 and will refill with tap water, then test again.
If Chlor is then needed I will add some ‘tasty’ Javel, and also some PH+ if necessary

Hi Paul, the chlorine test ignores cya so it causes some confusion. What we know is free available chlorine is mostly bound to the cya so not available to disinfect ( this point has been the subject of some disagreement over the years) but overlooking that hence why we need the higher chlorine level compared to what some books and internet pages say. Pool vinyl liner or glass fibre? If so, and your pH is pretty stable don’t add alk+ this would just mean having to counter pH rises later as the carbonates off gas from the pool. Good news is pH is not an issue provided it’s more than 6.9 as that can cause eye irritation. You can run your pool anywhere up to about pH8.5 without issue when you have CYA in the water. Different rules apply when the pool is not using CYA. This is because the compound of chlorine and CYA is the dominant source in the pool and not pH dependent. I posted some info on this a while back, might be worth you taking a look.

Thanks John, all useful information.
Our pool is a 10m x 5 m x1.2m throughout ,vinyl lined, Desjoyaux pool (that I converted to traditional filtration last year, which I wished I’d done years ago, but at 4000 euros you have to save up!)
The Color Q instruction leaflet quotes 0 - 10ppm recommended range for both free and total chlorine levels, so your reply indicates that I am doing the right thing by evacuating and re-filling with new water, and then not to worry if the Chlorine levels are the same as long as the readings are ‘comfortably’ below 10ppm and the CYA level is down below 100ppm?

Hi Paul, are you still using the salt chlorinator?

Hi John, Salt Chlorinator?, no, not me! Chlorine in it’s various forms.

Hi Paul, if you are not using a salt chlorinator then the advised CYA level is 30-50 with not much being gained above that level. The higher the CYA the higher the free chlorine level needs to be to provide sufficient to sterilise the pool.

The total chlorine includes the chloramines that you don’t want. If you subtract the free chlorine level from the total ( known as combined chlorine) then the result ideally is 0 more than 0.5 and you may be seeing the beginning of an issue (algae) when the chlorine level is high you may see a higher combined level so don’t panic but keep an eye on things.

Bonjour John. How can I get hold of a good testing kit, including for CYA, please.?

Hello Nigel and Welcome to the Forum.

Stella, Many thanks - do you know how I can contact John privately?

@John_Withall are you able to help @souleillat, please… ???:hugs::hugs::thinking:

I’ve set things in motion, now we just wait to see what floats to the surface :sweat_smile::joy:

Thank you, Stella.

On my way home now, pop back later

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Sorry for the delay, computer issue, now having to re install everything.

It’s probably the heat - :hot_face::upside_down_face::wink:

Weird win 10 thing. PC hung then l forced a re boot. Win started up with we are resetting the PC all apps will be lost!!

Hi Nigel,
Sorry for the delay, re installing takes longer than you think and still looking for some things!
Back to your issue. There are several kits on the market but over time I have tried to select the best kit for the money. The electronic testers take a lot of the guesswork away as they read and show the figure digitally rather than trying to colour match.

DIP strips are near useless and create more problems than they solve, they are cheap for a very good reason. Even an electronic DIP strip reader is hopeless as the original source (strip) is floored so a waste of money, too much variance.

Drop count (titration) testers are accurate if you don’t mind the measuring and counting, FAS DPD is good if you are acurately measuring chlorine.

The money side of things, several of the tester vendors package the kits to look cheaper than the competition by contain less testing reagents, some as low as 10 tests. This means you’ll soon be buying more reagents and if you add the cost of these reagents very often it’s more money that the better tester is at the start. The electronic ones I favour come with 100 test reagents, easily enough to last several years.

I can supply these kits but for forum rules please contact me directly to discuss further.

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How do I contact you privately to talk about this further?