Problem with PH

[teslarode]

Hello all,

First off, I'd like to thank you all for contributing to this great community, I have learned many new tricks & tips just reading topics on this great discussion board.

So here's my problem. I have a 15000 gallon in-ground plaster pool that I recently converted from in-line chlorinator to SWG. The SWG I have chosen is the AutoPilot Pool Pilot Nano+ which I have been using for over a month and overall I am very pleased with its performance. My problem however is the PH that is climbing high, which is what I somehow expected after switching to SWG, but my problem is, it is climbing at very fast pace. If I balance the PH let's say on Sunday, getting it down to 7.3, 3 days later, on Wednesday my PH is back to 7.8, sometimes even 8.0. So I have to mess with Muriatic Acid twice a week, to keep my PH in desired levels, and honestly I am not very happy about it and trying to find a solution to stabilize it...

I went to our local Leslie's Pool store to discuss this issue and they suggested that my TA is way low (testing around 70ppm) and that is causing my PH being volatile. I am not sure about this and I'd like to hear some expert opinion about this.

On the other hand I have been reading many topics about adding borates to the pool, that among other benefits would help me with my PH issue and I would definitely go for it, the problem however is, that I have a 3 year old kid that swims with me in the pool every day, and I can tell he swallows significant amount of water each swimming session (sometimes I'd say even 16-20fl oz. of pool water). Even though I am doing my best to teach him not to do so, he does swallow sometimes unintentionally and I would be very worried about his health if I add borates. I have also an infant daughter, that I am not taking into our pool yet, but most likely will next season where she would be about 15months old, and that raises another concern, for her small body to deal with borates...

I'd like to get some insights from you pool experts, what are my options, options that would be safe for my kids and in the same time would make my PH more stable.

Thanks in advance!
Dwayne


Btw, here's my latest water test results:

FC: 3.0
CC: 0.0
PH: 7.3 (just poured HCL to get it down from 7.8)
TA: 70
CH: 290
CYA: 50
PHO: 0

 

[Butterfly]

Welcome to the forum

I don't like handling MA, either. You might consider adding an acid pump for dispensing it.

If you continue to add MA to lower pH, the TA will drop over time (btw, 70 is not low) and help stabilize the pH rise.

We recommend TA of 60 to 80 for SWG pools.

If you have any water features, they will also push the pH up.

 

[Butterfly]

btw, how old is the plaster?

Also, the CYA is a little low and I suggest you increase it.
pool-school/recommended_levels

 

[teslarode]

I have a fountain but is set to pretty low (shoots about 5-6 inches high)

Plaster is about 1 1/2 year old (it's a pretty new pool)

Also worth mentioning, I live in Texas, so it's pretty hot and dry here. We got no rain for almost a month, so it's not the rain water neither, that would cause my PH to raise. I have to fill the pool weekly though, due to extensive evaporation, roughly about 300-350 gallons per refill from our tap, but I don't really think this would be another cause of my PH inbalance, as I did not have this problem when using chlorine pucks...

 

[jblizzle]

Pucks are very acidic, so they likely countered any pH rise. A SWG is just the opposite causing the pH to rise.

Have you tested the pH and TA of your fill water?

As was stated before, if you maintain the pH, the TA should drop some and the pH rise may slow down.

 

[teslarode]

Just out of curiosity I have tested my tap water. Here are the results:

PH: 8
TA: 80

As I mentioned before, I have to fill up my pool once a week (about 300 gallons per refill) due to excessive evaporation, but would 300 gallons of water with PH 8 affect my overall PH of 15K gallon of water ?

 

[chem geek]

On the other hand I have been reading many topics about adding borates to the pool, that among other benefits would help me with my PH issue and I would definitely go for it, the problem however is, that I have a 3 year old kid that swims with me in the pool every day, and I can tell he swallows significant amount of water each swimming session (sometimes I'd say even 16-20fl oz. of pool water). Even though I am doing my best to teach him not to do so, he does swallow sometimes unintentionally and I would be very worried about his health if I add borates. I have also an infant daughter, that I am not taking into our pool yet, but most likely will next season where she would be about 15months old, and that raises another concern, for her small body to deal with borates...

First off, borates are optional, but they do provide additional pH buffering. As for safety, there is detailed information about that in the Are Borates Safe to Use? thread. The EPA uses a margin-of-exposure (MOE) that is a factor of 100 (10 for inter-species variation and 10 for intra-species variation) so for an infant that comes to 1 tablespoon (1/2 fluid ounce) of pool water per day. A 3 year old weighing 31 pounds (14.1 kg) would have an EPA limit of 0.8 fluid ounces (5 teaspoons) per day. If one ignores the MOE and uses the No Observed Adverse Effect Limit (NOAEL) seen with male dogs, then for the infant this is 47 fluid ounces (just under 6 cups) while for the 3-year old this would be 84 fluid ounces (around 10-1/2 cups) and again, that is every day for months and still isn't when symptoms were seen with the dogs -- it's the highest level in the experiment where no symptoms were seen.

So it comes down to the MOE the EPA uses as a safety factor since there were no human trials for testing toxicity or chronic effects. It's up to you, but personally if I had a child that gulped that much water, I wouldn't put the borates in the pool unless I taught the child not to drink the pool water, at least not regularly. A single exposure or every now and then would be OK, but regular drinking of cups of pool water is not a good thing. And that's true in general even without the borates. There are disinfection by-products in pool water and while they are small in quantity, you don't want to drink pool water on a regular basis if you can avoid it. It's not about toxicity, but small increased risk and children tend to be more sensitive to environmental influences not only because of their body weight, but also because of their fast growing metabolism.