Constant Battle With Ph And Ta Using Spapure Chemicals

[Mike72677]

I've had a hot tub for about 2 months now. It's my first hot tub so I've been obsessive over testing the water. It's a small 3 - 4 seater and about 215 gallons. I've been battling pH at TA since day one. I've been using SpaPure chemicals (that's what my local vendor sells). I always seem to having a climbing pH and a falling TA. I also had problems initially establishing bromine only to find out a month later that my phosphates were about 3 times the max range.

Has anyone had experience with SpaPure products? Are they no good? Is there something else I should do, something else I should use? This past week I concentrated on pH and got it within range and it was staying there, but the TA continued to drop.

Below are my readings from when the local spa place tested my water.

10/24/2015 10/30/2015 11/7/2015 11/21/2015 11/23/2015 11/25/2015 11/27/2015 12/4/2015

Bromine (2.0 - 4.0 ppm) 0 0.5 0 0.1 0 0 0.1 0.5

pH (7.2 - 7.6) 6.7 7.7 7.6 7.7 7.8 7.9 7.5 7.8

Hardness (150 - 250 ppm) 0 120 200 220 190 200 210 210

TA (80 - 120 ppm) 0 110 70 50 90 40 50 60

Phosphates (0 - 500 ppb) N/A N/A N/A N/A 1750 0 0 N/A

[chem geek]

Climbing pH with falling TA when you add acid to lower the pH is a symptom of carbon dioxide outgassing. If you have spa jets, that increases aeration and increases such outgassing. You can minimize this by keeping the TA lower at around 50 ppm and supplementing with 50 ppm Borates for additional pH buffering and also don't try and lower the pH below 7.5 and instead target 7.7 to 7.8. The borates are most easily added using boric acid. Alternatively, you can look at standard spa pH "lock" products that are phosphate buffers, but they will precipitate a lot of calcium when first used.

The amount of carbon dioxide outgassing is related to how over-carbonated the water is and this is a function of pH and TA as shown in this chart where you can see that if you lower the TA and have a higher pH target then your water will be less over-saturated.

[Mike72677]

I keep all the jets closed and the air controls closed when it is not in use. However, I have 2 leg jets in the lounger that shoot straight up and break the surface of the water a little even on low. Do you think that might be the source of the CO2?

My pH down from SpaPure says to use Simply Soft to try and stop the pH/TA bounce. http://www.spapureusa.com/index.php/products/accessories/simply-soft/ Do you think that's good or do you recommend another product?

Last week I concentrated on just the pH, but my TA seemed to get way too low (not sure on the exact reading because I just have test strips for TA).

Thanks for the info and any more information is appreciated!

[chem geek]

Yes, that product will help because it's borates, mostly boric acid, but you can get that at a lower price at Duda Diesel or at The Chemistry Store. Up to you.

And yes, the leg jets breaking the surface exacerbate the problem.

[Mike72677]

Added the Simply Soft from SpaPure on 12/26/2015. I still have some TA decrease and pH increase, but not nearly as bad as it was. pH is usually 7.7-8.1 and TA is probably 30 - 50. I just have strips, so I can't get an accurate reading unless I take my water to the spa store. I also started turning the main jet control to the side without the leg jets in the lounger that were making the non-stop "fountain". I'm not adding pH decrease and alkalinity increase nearly as often as I was.

Do you think another oz of the Simply Soft might get my pH/TA locked? Thanks!

[chem geek]

Adding more won't lock the pH that much more. The EPA limits borates to 50 ppm (measured as ppm Boron) for safety reasons (margin of exposure of 100). Cutting back on the aeration should help reduce carbon dioxide outgassing that causes most of the pH rise.

[Mike72677]

Thanks for all of your guidance! This is my first hot tub and I've been obsessive about the water. With the history I've provided...how often should I check the water (I usually check it every day), at what levels should I worry about the pH and TA causing any damage? I have a digital pH meter so it's quick and easy for me to get quick, accurate pH readings.

The hot tub store I go to told me something along the lines of "dude, you're over doing it" when I went into detail about my readings, findings...etc. on my water issues. And other people I've talked to about their hot tubs don't really check their water. One person told me "I can lift the lid on my hot tub and know what it needs and I just throw a few handfuls of baking soda in it every now and then.".

While I don't agree with any of them...I don't want to do more harm than good by constantly adjusting my water. Thanks!

[chem geek]

If your TA is low (say close to 50 ppm) and your CH isn't too high (say less than 150 ppm) then you don't have to worry about your pH unless it gets above 8.0. Note that there will be less carbon dioxide outgassing at higher pH so the pH rise should slow down as the pH gets higher, especially with the borates in the water. With your testing you'll figure out how fast things change so can figure out how often you'll need to test and adjust.