ph low

[aylad]

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.

[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.

[aylad]

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

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

[wilcfr]

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.

[Watermom]

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.

[wilcfr]

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.

[wilcfr]

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?

[aylad]

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.