Low alkalinity and high pH problems


Old 02-22-12, 05:06 PM
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 3
Low alkalinity and high pH problems

I have been having a problem with our pH and alkalinity balance. Our hot tub cannot maintain a pH around 7.5 and 100 ppm alkalinity. If I get the alkalinity where it needs to be at 80 ppm (100 ppm would be ideal...) the pH goes way above 8.0. Dropping the pH to around 7.6 brings the alkalinity down to 20-40 ppm.

I really don't understand this as our water is very alkaline at 250 ppm and pH ~8.2 out of the tap. We have been using muriatic acid and sodium bicarbonate to make the adjustments but the water just won't balance. If I get the alkalinity up to 80 ppm and let the pH stay at 8 (where it seems to want to) then the water looks really good. If I get the pH to 7.6 (alkalinity is 20-40 ppm) then the water seems somewhat hazy.

Does anybody have any experience with this? Or any advice on how to remedy the situation?

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Old 02-25-12, 02:55 AM
Join Date: Feb 2012
Location: USA
Posts: 49
Yes, we have owned 3 HT's and after spending small fortunes on chemicals to keep the water balanced, I figured out with the gallon per water cost vs. chemicals, its just less expensive and easier to just dump the water every two months and keep it chlorinated with some bicarb added now and again. ...

Small bodies of water especially hot water like the 600 gallons in HT's, are extremely hard to maintain balance on. My job requires me to be a CPO and I have a 250,000 gallon Jr. Olympic and a heated 1500 gallon baby wading pool to maintain. ...

THe 1500 gallon pool is WAY harder to hold balance on, as the water volume is so low, the chemicals put in are "reactionary", to each other sporatically and never seem to calm down like they do in a large body of water..

I have found it easier with our 7.0 PH city water in working upwards in getting the TA in range. Working downwards from a higher PH is always harder. good luck.
Old 03-08-12, 08:00 AM
Join Date: Dec 2010
Location: USA
Posts: 332

Why are you trying to get TA in 100 range? TA is a buffer for pH and people try to get TA in specific range to keep pH under control. If your pH is under control I would not worry much about TA.

For hot tubs recommended TA levels are 50 to 80 and pH is 7.4-7.8. So if your pH is 7.6 and TA is 20-40 just let it be. As long as pH is stable, low TA should be ok.

Maybe you're concerned with CSI (Calcite Saturation Index)? CSI is influenced by TA and low TA will drive it down. Low CSI will be bad for pluster, tile, pebble and stone pools. CSI should be in -0.6 to +0.6 range, calculate yours and see where it's at.

edit: high TA could be result of either use of SWG or water features like waterfalls.

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