Can CYA be to high to stop SWG working

[magga321]

Hi All,

I have just moved into a new house with a pool and have taken over maintenance of it from pool company. I have installed a Hayward AQR9 AquaRite SWG but am having issues maintaining chlorine levels. When testing CYA levels with TF-100 kit i loose sight of the black dot well before it hits the 100 indicator. This is even after a 75% drain of the water. It used to disappear much sooner. I can only assume pool service company bumped stablizer level up as high as possible so that FC was maintained between weekly service visits.

I have done an overnight chlorine loss test and only lost about 0.5ppm so I don't think I have an algae issue. However the SWG does not maintain chlorine FC level over a longer period of time. I'm running pump for 12 hours a day with SWG at 100%.

A couple of questions:

1. Can having to higher CYA stop Hayward SWG from working correctly?
2. If initial FC level starts at lower than recommended levels for CYA will FC levels drop quicker

Its my understanding that the higher the CYA the less chlorine loss you should see. I would therefore expect SWG to easily be able to keep up.

Any help would be much appreciated.

Thanks
Ian

 

[Schadenfreude]

1. Can you post a full set of test results?
2. Was your SWG running when you did the overnight loss test?

 

[JoyfulNoise]

High CYA will not affect how an SWG produces chlorine. It will make whatever chlorine it does produce less effective since it buffers the active chlorine (hypochlorous acid) levels. But you'll notice that your very high CYA is doing one thing - whatever chlorine is being produced is being more effectively shielded from UV loss. However, that's little comfort if the active chlorine is at ineffective levels in the first place.

What does cause an SWG to stop producing chlorine - calcium scale on the plates and/or damage to the plate coatings. You should pull the cell and inspect it thoroughly.

I'm not familiar enough with the Hayward cells (but other experts here are), but if you post all of the diagnostic info from the unit while it is running, then others can help interpret what it all means.

Your primary task though is to get your CYA down to at least 80ppm. Pool service companies rarely understand how SWGs work and they typically refuse to give up on their standard practices of using shock powder and pucks. So its likely that the previous owner's pool service guy simply ignored the SWG and just practiced whatever routine chemical service they are most familiar with. You'll have a lot of work to do to undo all the "service" your pool has gotten....

- - - Updated - - -

By the way, and AQR-9 is completely undersized for a 15,000 gallon pool...the Hayward cells seem to be a little on the small side as compared to other cell makers but your pool would do much, much better with a T-15 cell.

- - - Updated - - -

Ah, my bad. I totally missed the fact that your cell is new. Even so, CYA alone will not affect production rates of chlorine. Let's see what your other test results are.

 

[Kiss4aFrog]

Welcome to TFP Ian

 

[magga321]

Thanks for responses. I cleaned the SWG last weekend so it should be good.
After 75% drain I had to add salt. The SWG reading is 3400ppm whilst test strips are reading just below 2900ppm. From what I've read I should trust the test strip over the SWG reading. So it could also be that my salt levels are to low.

Whilst reading around CYA on this site I came accross following method for testing CYA over 100 (Pool School - CYA). Will do this later on and work out how to drain to get CYA down to 80ppm.

Ian

 

[Kiss4aFrog]

That would be the correct procedure for doing the CYA dilution test for levels beyond 100.

Fill the mixing bottle to the lower mark with pool water.
Continue filling the mixing bottle to the upper mark with tap water.
Shake briefly to mix.
Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark.
Continue the test normally from step 3, but multiply the final result by two.

If your CYA is really high would it make more sense to get it into that 70-80 range before adding salt to the present water that you're going to need to dump to lower the CYA


" I can only assume pool service company bumped stabilizer level up as high as possible so that FC was maintained between weekly service visits."
If you're CYA was so high it's still over 100 with a 75% drain, it was so high I doubt the chlorine in there was able to do it's job. My guess would be it got that high because of the chlorinator they chose to use. Like tablets and or powder that contain CYA.