Freeze Guard and Waterfalls; Aeration effect on pH

[E&J]

I have a 23K In-Ground pool, with a 7 ton rock waterfall. Freeze guard was on most of the last two weeks and my TA dropped to 50. I added 13lbs baking soda. Next week, TA dropped to 60. added another 13lbs of baking soda. I have an 2 tank intellichem setup, which injects liquid chlorine and Muratic acid as needed. I went through about 2 gallons of muratic acid each of those last two weeks. I can only assume that the pH rose due to the aeration effect of the waterfalls on constant during freezing weather, and the Muratic acid consumed my TA.

Is this normal or I am chasing my tail here?

I have a plaster bottom, Rock waterfalls, 2 SVRS intelliflow pumps, one for filtration, one for waterfalls, cartridge filter, ozonator 2 skimmers, Pentair heat pump.

Water is checked 3 times a week- in summer, I consumed approximately 3-4 gallons of liquid chlorine a week, and about 2 gallons of muratic acid. Installed the intellichem and ever since it was installed, I have been filling muratic acid and dosing the pool with baking soda. My friend, who also subscribed to this forum, had his pool operating all summer, but switch to liquid chlorine mid summer- still says his TA stays fine, and he hasn't had to add any baking soda to his pool. I'm just wondering if I'm screwing up. I'm a new pool owner, just built last year, and I'm in a lawsuit with my builder, so he's no help..... Pool store says my water's great every time I go in, but thinking they may be laughing all the time, because I keep buying products when I run out.

chlorine- 2ppm
PH- 7.4
TA- 100
Calcium hardness 360
CYA- 60

(Been working to get the hardness down, and the CYA down- the pool builder put the CYA in (too much in my opinion, and they installed an erosion feeder, using triclor tabs). After they left me, I had the intellichem system installed, but the technician who installed it had little/no experience with it. Pentair Tech support set me up, and they are borderline on whether my consumption of Sodium Bicarbonate/Muratic acid is "in-line" with what I should be expect.

Water is beautiful, easy enough to deal with, just wondering if my chemical consumption/costs could be lowered without sacrificing on water quality, safety and keep my pool and equipment in the best condition.

Thanks,

E&J

 

[JVTrain]

Are you always striving to keep the pH that low? I would set your MA feeder so that your pH is more consistently at 7.6-7.8 or so. Verify that this doesn't throw your CSI too far out of range to scaling, but it shouldn't with your CH and TA levels. Carbon dioxide outgasses more slowly at higher pH levels so maintaining at a higher pH most of the time will lead to less outgassing, less pH rise. The constant waterfall running was working against you but maintaining a lower pH can be hard on TA as well.

 

[JasonLion]

Lowering your TA, or letting it go down on it's own, will reduce the amount of PH drift you experience, which will reduce the amount of acid you need to use.

 

[E&J]

Are you always striving to keep the pH that low? I would set your MA feeder so that your pH is more consistently at 7.6-7.8 or so. Verify that this doesn't throw your CSI too far out of range to scaling, but it shouldn't with your CH and TA levels. Carbon dioxide outgasses more slowly at higher pH levels so maintaining at a higher pH most of the time will lead to less outgassing, less pH rise. The constant waterfall running was working against you but maintaining a lower pH can be hard on TA as well.

Good Point- Being new to pool maintenance, I assume(d) that keeping each of the parameters in the dead middle of the acceptable range was preferred so that you have margin on both ends. Iam rethinking this, based on your feedback....

I recently bumped up the set point on the intellichem to 7.6 (from 7.4) because when I tested the water with my kit, it was showing 7.2. I knew when I added the last 13lbs of Baking soda, my pH increased, but the MA injector didn't run much. After I checked it again the next day, the pH on the intellichem was showing 7.6, but my manual test showed 7.4. Because it seemed like I still have a .2 difference in the Intellichem's reading of pH and my manual test, I altered the sensitivity of the Intellichem pH- bumped it down by .1 of a point (pH showing 7.6, but with the alteration, it shows 7.5). I only moved it down .1 point because my water test were showing <7.5 (but there isn't enough precision in my comparator) to show how far. During the summer, the pH from the Intellichem readout matched exactly to physical test. I cleaned the probes with hot soap and water, but it had no effect on readings.

Enough on background: Given my readings and environment, what do I need to change (other than allowing my pH to float up a little from where I was and allowing my TA to drop a little below 100). Is the CYA high? Is CH high?



Thanks so much for the feedback.... This site is a wonderful resource!

 

[pwrstrk]

Welcome to TFP !
What test kit are you using ? If these test results are from one of our recommended Test Kits then, your CYA isn't really high at 60 ppm. 50 ppm is the high end of the range for a non SWG pool. Your FC is too low at 2ppm. You should be targeting an FC level of 7-8 and never below 5 with a CYA level of 60.
Your CH level is fine. If these are pool store test results since you mention going to the pool store, all bets are off !
Also if you could add all your pool and equipment info to your sig that will help us help you better. Thanks !