ph low

Hi, I have a 70,000 gallon inground pool. My ph is 7.2 fc 9.8 tc is 9.8
hardness `190
alk 120 cynaric acid 120

I am not sure how the calcualtion works to figure out how much borax to add to up the ph. I would also like to know if a person can get a stomach ache from swimming with the cholorine that high. Is it dangerous??
The other thing, is how often do you need to put bleach in your pool before you have to check and add more? Can I get the calculation? I found an area where it said BBB but I lost it!!

Hi Timmie,

Your pH at 7.2 is in the acceptable range--I wouldn't mess with it unless you have problems with it falling. Are you using trichlor pucks to chlorinate with? Your CYA is awfully high, indicating that you are either using trichlor or dichlor, both of which will drive your pH down. If you switch to plain bleach, you'll find that your pH will probably rise a little on its own. I do suggest that you don't use either trichlor or dichlor at this point, because they also drive your CYA up, and it's already very, very high.

Just another comment, with your CYA at above 100, then you need to keep a MINIMUM of 8 ppm chlorine in the pool to keep it sanitized, and can safely keep it as high as 15 or so. So your 9.8 chlorine is fine, and should not cause stomachaches. If you lower your CYA , then you can safely lower your chlorine levels without algae blooms, but this can only be done through partial drain/refills.

How often you need to add bleach to your pool depends on your bather load, other "stuff" that is introduced to your water, and your cya and beginning chlorine levels. Obviously the more chorine that's used, the more often you'll have to add, but that tends to be different with each pool. I personally suggest that you take the time to test for chlorine daily, adding more when you find your levels at 8 or below. It won't take long for you to develop a feel for how often you're going to have to add it.

Janet

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Originally Posted by aylad

So your 9.8 chlorine is fine, and should not cause stomachaches.

Janet

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I picked up on this in your post. Can chlorine cause stomachaches? If so, under what circumstances?

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Originally Posted by poolmimi

I picked up on this in your post. Can chlorine cause stomachaches? If so, under what circumstances?

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No, chlorine doesn't cause stomachaches under any circumstances. (Except maybe if you drank several gallons of pool water, and then it would be the water and not the chlorine that causes the problem! :) ) I only mentioned it because timmie specifically asked about stomachaches in his post.

Janet

Hi, thanks for the reply!! I have been using the pucks this year. Last year I did not and had not problems with my pool.
When I add bleach, Do I add one gallon per 10, 000 gallons of water? We go by litres in Canada, so the formula would not be hard for me to figure out.
What is the acceptable range for PH?? I was told that it could be on the low side as opposed to the high side, is this true??
Thanks
Oh, I am getting a new heater etc for my pool. The one I have is 30 years old, and came with the house. Though the pool is in great shape, the heater does not work on a set heat. I decided to get the heater and all the bells and whistles. It will make pool time easier!!

In a 70,000 gallon pool (wow, is it really that big? That's HUGE!) it takes 1 gallon + 3 cups of 6% bleach to raise your Cl by 1 ppm. You'll need to keep it at no lower than 8, with an approximately max of 15 to keep it clean and algae free.

pH range should be 7.2 - 7.8. Generally, lower is better, but don't let it go below 7.0 or you could start having problems with your pool and corroding your new heater. 7.4-7.6 is a good target to shoot for.

Janet

Edit: There is a bleach calculator on this forum that will help you figure out how much to add. Search the forums using the adanced search feature for "Bleachcalc". The 3rd or 4th post on the list called "Bleach calculator" has the bleachcalc link in it. It works for me when I click on it, but for some reason when I try to copy it to this post it won't work. Download it to your desktop--it's a handy thing to have.

What's the pitfalls of running the PH a bit high, around 7.8? That seems to be where my pool likes to sit.

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Originally Posted by Spensar

What's the pitfalls of running the PH a bit high, around 7.8? That seems to be where my pool likes to sit.

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That's about where my pool likes to settle if I don't mess with it, too. Ben always held that the chlorine is more effective at the lower pH levels. However, my daughter reports less eye irritation when I let it stay higher.

You can't let the pH get high if you have a high calcium level, or if you have metals in the water that you're trying to keep from staining the pool. High pH and/or high TA will tend to make calcium flakes precipitate out of water that is very high in calcium, causing a milky pool, and high pH will help the metals "fall out" of the water and begin to stain your pool. Otherwise, it doesn't hurt anything that I know of to let it stay at the higher end of the range.

Janet

I would like to add a question. We have a 38000 gal. gunnite pool. We chlorinate with 3 inch tabs and shock with calcium hypochlorite. For years we had a problem with high alkalinity levels (200+), this year however that is not a problem (102), but we are having problems with our pH. Our Cl levels have stayed around 2ppm all summer, but we can not get or keep the pH above
7.0. Early in the season we were running around 7.1-7.2, but in June it dropped to around 6.8-6.9. We have put a lot of Borax (3.5 boxes) in the pool over the course of the season with little change. As I mentioned earlier our usual problem is Alk. not pH. Any suggestions would be welcome. We bought some soda the other day, but would rather not use it because of past issues with high alkalinity levels.

The pool is crysal clear with no algae problem, but the pH issue concerns us because of possible damage to our heat pump pool heater.

Using trichlor pucks is probably your culprit as they are extremely acidic and will drive your ph down. When your ph appeared to drop to 6.8 earlier, it might actually have been much lower than that as most test kits don't show anything lower than that reading. You don't mention what your cya reading is, but if you have been using trichlor it may be really high. If that is the case, a chlorine reading of 2 is pretty risky. At any rate, continue adding Borax. Wait 4 or 5 hours between doses to let it mix well, then retest and redose until you get your ph between 7.4-7.6. Also, test for your cya level and repost with that info. If you find that your cya is really high, you might want to consider using something else other than the pucks to chlorinate with as they will continue to add cya. Hope this helps.

Just to add a word to Watermom's advice, I would also bring the alk up to the 120 range. When using trichlor, the higher alk will help keep the pH from swinging so far and so fast. The fact that you had high alk before is probably why you didn't have as much problem controlling your pH as you do now, with lower alk.

Watermom thanks for the suggestions, we use a pH meter to check the pool, it was a cheap investment to get a much more accurate reading.

Aylad with that in mind maybe we will give the pool a little dose of soda. I have forgotten when you want to up the pH but not the Alk do you broadcast or put it in the deep end?

Sal soda will raise both pH and TA. It does not matter if you broadast it or put it in one place. You are thinking about the 'slug method; of lowering TA, which has been proven NOT to work. All slugging acid does is ruin the pool because of the pockets of very low pH created.
Baking soda will raise TA and cause a slight rise in pH compared to sal soda
Borax will raise ph with minimal impact on TA.

As far as your pH meter, are you calibrating it on a regular basis and storing it with the electodes wet? pH meters are only accurate if they are regularly calibrated against standard solutions and if the electrode is properly cared for. The ONLY kind of pH meter I would trust is one that uses a 3 point calibration (calibrated against 3 different pH standard solutions.)