SWG and Ph balance

[DennyB65]

I have had an aqua rite system for about 6 months now. I know these systems tend to cause ph to drift upward. However, I have been adding 2 cups of acid every other day to keep it around 7.4. This seems like alot of acid to me. Has anyone else experienced this situation?

[waterbear]

What is the size and finish of your pool (plaster, vinyl, fiberglass?) and how new is it. These are all factors that need to be taken into consideration. The upward pH drift is normal becuase as the cell generates chlorine it also produces sodium hydroxide as a byproduct. If you pool is small and fiberglass or vinyl a pint of acid a day seems excessive but if it is a large, new plaster pool perhaps not.

[tonyl]

I've had the AquaRite for about 5 years now and the Ph will definitely rise and although you can't stop it, it seems to level out at about 7.8

Rather than fight it every other day, you might let it drift up a bit higher then knock it down to 7.2. For my 20K pool I'm adding acid (1/2 gal) once a week in the heat of the summer. I personally don't think it's critical to keep the ph low and steady as the FC within the cell itself is reportedly 100 ppm~ and my experience has been it sanitizes effectively even if the ph is a hair over.

So I've pretty much learned to relax and enjoy it. Check your water a couple times a week but don't panic to keep it 7.2-7.4, etc. In going on 5 years I've never had an algae outbreak and my water gets 90 in the summer. (My wife likes the heater~)

Hope this helps, Tony

[DennyB65]

My pool is diamond brite surface and is about 12k gal. It is 6 months old so i figured I would be past the period of high ph due to the new surface. Thanks for the info.

[mwsmith2]

The pH will continually rise, I think what you are observing is measurement error on the part of your pH test. The color changes aren't as distinct at higher pH levels. Higher pH usually leads to scale formation, and that's not good for the SWC cell. I generally dump 1 quart of acid in the pool weekly, and that keeps everything happy.

Michael

[kjsmom]

This begins my 3rd year maintaining our pool and I've done well (due to the Forum, thanks), but I'm STILL confused. We have an Aquarite SWG. Aquarite recommends a FC level of 1-3ppm. The first year, I maintained that FC level and had no problems whatsoever. Last year, I kept the FC level around 5ppm, (my CYA was around 30-50, which is below Aquarite's recommended 60-80ppm), and I had some trouble with the pH drifting up. So, my questions are:
1) Is a FC level of 1-3 ppm too low? (The liner mfg also recommends that level.)
2) Do high FC levels cause the pH to drift up?
3) I understand how CYA affects the "shock" FC level, but I don't understand what CYA has to do with maintenance FC levels, other than keeping the CL from disappearing too quickly. In other words, with a CYA of 30-50, why is a higher FC level required than if the CYA is 0?
4) Why does Aquarite recommend the higher CYA levels? According to the "Best Guess" cya chart, with a cya of 80 I'd have to maintain FC of around 8, which I'm afraid would be hard on my liner.
5) How can Aquarite recommend a cya level of 80, and a FC level of only 1-3ppm?
Thanks!
PAT

[mwsmith2]

There is no "trouble" with your pH drifting up (other than needing to keep it down) it's part of the normal operation of a SWC. The cell produces a small ammount of caustic as part of the electrolysis method of making chlorine. It's ALWAYS going to drift up.


The reason higher Cl is needed with higher CYA levels is because CYA inhibits the action of the Cl.

I don't know why they want 80 ppm CYA. I run mine at 40 with no problems.

Michael

[kjsmom]

Thanks Michael --
Needing to keep the pH down is just the trouble I'm talking about. So, if I maintained lower FC levels, the cell would produce less chlorine, and thus less "caustic", and the pH drifting up would be minimized???

Has anyone followed Aquarite's recommendation of 80 CYA and FC of 1-3ppm? I'd sure like to hear how that has worked out! I thought there used to be an Aquarite sales rep on the forum. Might he still be around?

Thanks again.

PAT

[Poolsean]

PAT,

I'm sure Aquarite's results are the same as AutoPilot's. Maintaining 80 ppm cya and 1-3 ppm chlorine is not a problem. It just does not react like a majority of poolforum pool owners that must maintain higher FC with higher cya.
Rest assured, I have a ga-zillion salt customers maintaining their pools with these parameters.

[mwsmith2]

Thanks Michael --
Needing to keep the pH down is just the trouble I'm talking about. So, if I maintained lower FC levels, the cell would produce less chlorine, and thus less "caustic", and the pH drifting up would be minimized???

Yes. But why? I run mine at 40% and drop 1 quart of acid in it a week. I'm not sure what the problem here is? Any time you add Cl in any form, you are going to affect the pH:

• SWC increases pH
• Bleach increases pH
• Di-Chlor/Tri-Chlor decreases pH

Running your pool at lower Cl levels is a sure way to create a problem waiting to happen, either with algae or sanitation. Run 3 - 5 ppm Cl, dump in the acid for the pH and be happy!

Michael