SWG is not making pH go up

[semenzato]

It is partly true that the Borax will buffer the pH so that when you do add acid you will be adding more than if the Borax were not there, but as waterbear points out there are reasons why the total amount of acid needed will be lower. Borax has a double-effect -- it's both a pH buffer AND an algaecide and the latter allows for less chlorine and less chlorine means less SWG on-time and less pressure on making pH rise.

Your TA will eventually drift downward and the pH will slowly drift upward. Anyway, if you CAN test your TA (and CYA level, if you can, though TA is more important), that would be helpful -- not to solve any problem, since there isn't any, but to help confirm or refute what I believe is going on. I always want to compare the "theory" against real-world behavior.

Thanks,
Richard

Thank you and sorry it took me so long, but I finally got around to measuring the alkalinity and it seems fairly normal at 140 ppm.

[chem geek]

Wow, that's actually high (for SWG pools) so that must mean that the Borax is REALLY potent for cutting down the pH rise (and that's what waterbear sees as well). It may also be that the very still air in an indoor pool helps so the aeration may be very, very low. It's interesting, in any case. Thanks a lot for the update!

Richard

[semenzato]

The pool is almost always covered with a solar blanket (bubble wrap). This is a necessity or the humidity in the room would be unbearable. I suppose this could prevent the hydrogen from being released, and perhaps it forms bubbles under the cover which are readsorbed in time?

Thanks!
Luigi

[chem geek]

Maybe. But others with covers still experience a rise, but those are outdoor pools. Maybe your bubble pack is different and as you say it keeps a layer of higher concentration carbon dioxide under it, but the gas does have to go somewhere in any event.

Another reason you probably don't see as much rise is that as an indoor pool your SWG is running far lower than in an outdoor pool because there is no sunlight to breakdown the chlorine. This is partly why we think the Borates also help -- not only as a pH buffer, but also as an algaecide to lower the production of chlorine. When waterbear added Borates, he found he could lower the output of the SWG.

Anyway, lots of reasons -- don't know which ones are most important -- but it's good news at any rate. We do know that we have at least two solutions that both work and work even better together -- lower TA and use of Borates. That's good enough for now.

Richard

[steveinaz]

I've noticed the same thing since my SWCG was fired up. PH seems to be stable for much longer. Where I used to add about 2 cups of muriatic every 3 days, I'm now only adding 1 cup a week.

[chem geek]

Steve,

You list that you have a "waterfall" in your pool. By any chance, is that waterfall being run less when you turned on your SWG? The waterfall would do a lot of aeration and cause the pH to rise. Over time, the aeration plus acid additions would cause the TA to drop and there would be less and less pH rise over time, but this would take a long time to accomplish. Was there anything else that changed, including chemical additions, the TA level, or the pH? If you turned on your SWG and found the pH to be more stable, then that is indeed out of the ordinary (based on posts from users) and would be useful to figure out.

Richard

[steveinaz]

Steve,

You list that you have a "waterfall" in your pool. By any chance, is that waterfall being run less when you turned on your SWG? The waterfall would do a lot of aeration and cause the pH to rise. Over time, the aeration plus acid additions would cause the TA to drop and there would be less and less pH rise over time, but this would take a long time to accomplish. Was there anything else that changed, including chemical additions, the TA level, or the pH? If you turned on your SWG and found the pH to be more stable, then that is indeed out of the ordinary (based on posts from users) and would be useful to figure out.

Richard

The only time we run the waterfall is when we are swimming, to keep people from stubbing a toe on the floor jets. We haven't done anything else different aside from stopping use of Clorox. Maybe it's just a coincidence of my TA slowly lowering?

My last TA reading (done 2 weeks ago) was 140. Using waterbears formula for correction, that would put my corrected TA at apprx 122. (Given a CYA of 55ppm). Don't know if that helps...

Latest:
FC 7
CC 0
PH 7.6 (maintained thru adding 1 cup muriatic a week)
TA 140
CH 295
CYA 55

[cschnurr]

Richard,
Without trying to hi-jack this thread, I would like clarifcation one of your previous posts. You mentioned that

"A low TA (adjusted for CYA) could help explain your lack of pH rise"

Where can I find info on this adjustment and does my Taylor K2005 measurement already include this adjustment.

Thanks
Carl

[waterbear]

The CYA adjustment forumula is included in the back inside page of the booklet that came with your Taylor kit. To simplyfy it just subtract 1/3 of your CYA reading from your TA reading if your pH is between 7.4 to 8.2 and subtract 1/4 of your CYA reading from the TA reading if your pH is 7.0 to 7.2. The result with give you your adjusted TA. It will be close enough!