pH shot up with just two cups of borax!

Hey everyone, I've got a weird pH issue. Running a 3871 gallon Intex vinyl pool with a SWG, and the pool water has remained (and still is) crystal clear. Initially I had trouble keeping the chlorine level above 1, but after 1/3 pound of dichlor and continued daily operation of the SWG, it's staying in the 4 to 5 range.

My problem is pH. It's always been on the low side, 6.8 to 7.0. Yesterday I added about a cup of borax and it barely budged. Today I added two more cups and it shot up to the 7.8 to 8.0 range. Testing was done about an hour after application. What did I do wrong? Browsing around this board I see people adding entire boxes of the stuff and barely getting results. Did I just not wait long enough before doing the second test?

Additional information: I added the borax by slowly sprinkling it in at the return jet (because I don't have a skimmer basket). I am testing chlorine and pH using the HTH 3-way test kit.

Size matters :)

Putting a whole box of 20 Mule Team in a 20,000 gallon pool is different from putting 3 cups in 3,800 gallons. Do you know what your total alkalinity is?

TA is 120. After 24 hours pH is still hovering around 8.

TA is good. Do you still add dichlor now and then? That will help lower the pH a little. It also will raise the CYA (stabilizer). Do you happen to know what that number is for your pool?

You can get a small container of "pH Down" or "pH Minus" at the pool store. It's dry acid. The instructions are on the container and are probably given per 5,000 gallons so you'll want to use less. A good rule of thumb is to use 1/2 of any chemical, wait a couple hours, test, adjust.

We have a Sticky for using muriatic acid to lower pH but it involved buying a gallon of acid and you'll never need that much over the life of your pool. The dry acid product from the pool store is more suitable for your situation. It's not expensive, it's easy to use, it stores well across seasons, and for small systems it's more efficient. Just go easy on the amount.

I haven't added any more dichlor because the SWG has been maintaining the chlorine level just fine without any help. But if it will lower the pH a little then I will give it another small dose. Unfortunately I do not have a CYA test.

Thanks for the dry acid suggestion. Buying a supply of muriatic would definitely be overkill; this is a seasonal pool and I really only need to get through the next five weeks or so. The water is already beautiful, so I just want to keep it safe and avoid doing anything that would wear down the liner so I can put it up again next year.

Rising pH is also an effect of the operation of the SWCG, and is something that you'll always see as long as you use it. If you'll drop your TA to the 70-80 ppm range, and drop your pH to 7.6, it should help it stay more stable, although it won't stop the rise altogether. Adding acid on a routine basis to combat the pH rise is one of the only water maintenance issues with a SWCG.

Janet

yeesh ... I can't win. I added dichlor and dry acid at half the recommended amount for my size pool and my pH swung all the way back down to the acid end of the scale. Dunno whether I should try microdosing with borax or what. Would leaving the cover off (particularly during a rainstorm) tend to raise or lower the pH?

Aeration of the water, and operation of the SWCG, should both work to raise pH. However, if it's below 7.0 now, you need to get it back up above 7.0 ASAP using small doses of borax. Aeration doesn't work quickly enough when the pH is dangerously low.

Quote:

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Originally Posted by IGnatius T Foobar

...Would leaving the cover off (particularly during a rainstorm) tend to raise or lower the pH?

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As aylad suggests, aeration (raindrops) will tend to raise pH but, in my pool, rain usually lowers pH (acid rain). Definitely follow aylad's advice and bring the pH back up with small amounts of Borax.

How small?

What's the correct dose of borax to move the reading just a little bit on a 3861 gallon pool?

Two Cups was way too much so... try a half Cup at a time, let it dissolve / mix for a couple hours then retest.

Quote:

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Originally Posted by BigDave

Two Cups was way too much so... try a half Cup at a time, let it dissolve / mix for a couple hours then retest.

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. . . but we know that, only because of the results . . .


Sounds like a 1 cup dose might be it? The pH rise you experienced is not expected for a 3500 gallon pool with a TA=120.

See Pool Chart link below -- complete it, so we know more about your pool, and PARTICULARLY, about how you tested. -Ben

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+ It's much easier to answer your questions, when we have the details about your pool in one place. We often 'waste' the first few posts back and forth collecting information. So, please complete our new Pool Chart form -- it takes about 30 seconds, but will save much more than that.

Pool Chart Entry Form

Thanks everyone; I gave it a 1/2 cup dose this morning and I'll check the results tonight. Pool chart has been completed with references to my user id and this thread.

Quote:

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Originally Posted by IGnatius T Foobar

Intex "guess strips" for TA;

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I think that may be why your pH shot up -- you have bogus TA measurements; most likely your ACTUAL TA is much lower. :puzzle:

Posting test kit nag . . . ;)
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+ Get a cheap OTO (yellow drops) / phenol test kit, or if available at YOUR Walmart (check availability), get the HTH 6-way DROPS test kit, which is compatible with the Taylor K2006. Test the pool as soon and you can, and post the results. If you get the 6-way kit, ALSO test the water you FILL the pool with, especially if it's a well, and post THOSE results as well. (The HTH is the best available kit you're likely to find locally, but it's not the K-2006. It can only provide rough measurements chlorine levels above 5 ppm, and it measures "TOTAL" hardness, rather than "CALCIUM" hardness, which is not ideal.)

+ Having a good test kit makes pool care easier for EVERYONE, but is an ESSENTIAL tool for pools with problems. A good test kit means a kit that can test chlorine from 0 - 25 ppm, pH, alkalinity, calcium hardness, and stabilizer with reasonable accuracy. Test strips (AKA 'guess-strips' ) do NOT meet this standard. Some pool store testing is accurate; most is not. The ONLY way you'll know whether your pool store is accurate or bogus, is by testing accurately your own self. On the other hand, pool store 'computer' dosing recommendations are NEVER trustworthy -- ignore them. They are designed to sell more chemicals than you need, and WILL cause many pool problems.

+ We recommend the Taylor K-2006 test kit, which meets the requirements above, for many reasons. The HTH 6-way drops kit is a great starter kit, and is compatible with the K2006 (it's made by Taylor). There are a few alternatives; for example Lamotte makes an FAS-DPD kit that's OK -- but it costs 3x as much. But, we're not aware of any test that is better, and since we are all familiar with the K-2006 (and can help you with it) we recommend it exclusively ( Test kit info page )

One caution for the 2012 season: Amazon does not stock the kits directly. So when buying at Amazon, Amato is our current preferred seller. However, they often don't list enough stock to last the whole day, so try order mid-morning. You should expect a delivered cost under $60 for the K2006A and under $95 for the K2006C. If you can't find that, wait a day.

+ Here are links to the kits we recommend (you can check local availability on the HTH kit, using the Walmart link):

HTH 6-Way Test Kit @ Walmart
Taylor K2006A (3/4 oz bottles) @ Amazon
Taylor K2006C (2 oz bottles) @ Amazon

Thanks for all the help. We have the pH up to 7.4 now, with a daily dose of borax added with a dixie cup. :)

Since we only have another 3 to 4 weeks of swimming season left here (partial shade and no heater) before we drain and store the pool, hopefully we'll now manage to keep the pH stable without any large changes. I've gotta say the SWG is a technological miracle -- it's kept our chlorine level sufficient and the pool water crystal clear all season without a lot of effort.