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I came across this anomaly in another thread in this forum I think and have not yet been able to find a reason for the steady pH in vinyl pools.
If you could post a complete analysis, and mention the chemicals you add on a regular basis, it might help to get a better insight. Also what you do when there is an upset through bather load, weather conditions, etc.
Pat
The 1st thing you need to know to understand stability or lack therof is the chemistry of your make-up water. My make up water comes out of the tap above 7.8 and that's part of the reason I add acid on a regular basis. My pebble sheen is still less than 2 years old, so it may still be driving the PH up as well. I use about 2 gallons of acid a month in a 14,000 IG pool
I have a fiberglass pool, my fill water has a pH of 7.2 and an TA of 110. My pool also has TA of 110. I have to add acid every 3 weeks to get my pH to 7.2. After 3 weeks it goes up to 7.6 or slightly higher and I add acid again. Run my cell at 5% output with 8 hours of run time to maintain 3ppm FC. Still a small price to pay for the sparkling water I always have with the SWG! I would think that the non reactive surface of fiberglass would be similar to vinyl but my pH does rise. Granted I have to add very little acid when I do. 1 gallon lasts close to 6 months!
The only chemicals that I add are ph+ (sodium carbonate) and ph-(dry acid) from pool store. This is my first season with SWCG, used to use Baquaglop. I have not yet had an upset through a heavy bather load and I really do not do anything but vacuum after bad weather conditions, I just let the extra water evaporate. My latest test results are 5ppm FC - PH 7.4 - TA 120 - CYA between 60-70 and Calcium hardness at 250.Quote:
Originally Posted by PatL34
Quote:
Originally Posted by boscogabby
I see from your two posts above that you use ph+ and pH-. This tells me that you are using up salt for the process, and will eventually have to add some when the low salt alarm comes on. Dry acid is acid but in a different form, as it dissolves to form sodium sulphate and sulphuric acid. No problem in that but it tends to skew your argument regarding not having to add acid.:(Quote:
Originally Posted by boscogabby
The total dissolved solids will increase in the pool accordingly, and may well be assisting the TA in acting as an extra buffer to minimize pH bounce. This is just a theory on my part. Someone with better chemistry than I, hopefully may enlighten us further.
Pat
Here's a link to our earlier thread about vinyl pools and pH drift with SWC's:
http://www.poolforum.com/pf2/showthread.php?t=1188
My pool is running closer to the typical SWC operation now that it is in full use. My ph does drift up now over 2-3 weeks (give or take) from 7.2 to 7.6.
When I do knock it back down, I'm having to use a full gallon of acid instead of the 30 oz. the bleach calc predicts, so my water appears to be pretty highly buffered.
Regardless, I absolutely love the SWC. I never dreamed pool maintenance could be this easy. :)
It was not so much an argument as it was curiosity on my part as to whether or not I was doing something wrong. Should I not use PH+ and PH-? What do you mean by up salt?Quote:
Originally Posted by PatL34
I meant that you were using up the salt in the pool, and would have to add more later on. By using Muriatic Acid only, you maintain the salt level and raise the pH at the same time, "killing two birds with one stone".
Hope that clears it up. Read the "SWCG Operation" at the beginning again and you will see what I mean.
Pat
A few posts back it was suggested to measure salt levels every week.
I just put in a new Autopilot digital last week and it will display the salt level. Mine shows 2800 which agrees exactly with the test kit. It also says to add 36 lbs of salt, which it calculates from the setup page where you put in your pool volume.
I keeps getting better and easier.
If you really want to blow the bank, you can add on the ORP kit and an automatic muriatic acid pump .... totally auto.
If my PH is steady at 7.4 and my water is balanced and clear should I add some Muriatic acid to maintain salt levels as part of the process? Should I bring the PH down to 7.2 or just leave it alone? I have not had any problems with low salt levels or anything for that matter. The pool is inground vinyl liner about 8000 gal. FC-10 / Ph-7.4 /TA-110 / CYA-60-70/ CH-250. Pump runs 12hrs a day with Aquarite set at 20%.