What is going on with my PH level?

[liulady]

Hi all,

First of all, let me say how very much I appreciate ALL of the information from this site and forum. Over the past couple of weeks I've gone from being completely clueless about how to manage our 16X48 5,000 gallon AG Intex Vinyl pool to draining (sky-high CYA), slamming and having a crystal clear pool! YAY!

But, I'm still in the testing (with my new Taylor K-2006 kit) every day mode as I continue to sort it all out.

When I refilled the pool, the PH level right out of the tap was sky high. In fact, I went and purchased the chemicals to lower my PH. But, by the time I got back from the store and retested to find out how much to add, the water had already settled down enough that the PH was dropping. By the next morning, the PH was in the 7.8 range. So, I returned those chemicals.

Today I tested and my PH was LOW. It registered lighter than the bottom color on the test kit. So, I plugged in "7" into the pool math calculator and added the suggested amount of 13 oz. (by volume) of Soda Ash to raise my PH to 7.5. I was trying to be "reasonable". Several hours later though and the PH is testing a bright shade of hot pink! It is not even on the chart.

So, I'm trying to figure out what I did wrong. I thought I was following the "rules"! My TA was low as well when I added the Soda Ash (60 ppm). It is now at 80 ppm. My other levels are as follows:

FC 7
CYA 50
CH 20

(Haven't tested for combined chlorine in a couple of days. It was 0 a few days ago)

Thanks for any thoughts you may have. I will definitely add about half the recommended dose from now on. I really hate to go to the pool store and re-purchase the chemicals to lower the PH...

Beckie

 

[Divin Dave]

Hi Beckie,

the stability of pH is dependent upon the TA. It very well could be your TA is way out of whack. Can you post up a complete set of test results for us?

As a FYI, pH is one of the things that you very likely will have to adjust very regularly, so its good to have chemicals for that on hand.

Most of us use Muriatic Acid to lower pH. It can be found at about any hardware store in the paint department. Make sure to get the 31.45% strength.
There is some out there that usually say "green" or something like that, which is about 1/2 strength that costs the same, which is not a good value.

Also, as a FYI, using chlorine pucks will drive the pH way down. This is one of the reasons why we dont recommend using them as a source of chlorine.

 

[Texas Splash]

Hi Beckie, and welcome to TFP. I tried to duplicate what you experienced on the Poolmath calculator, so let's compare numbers. I made sure to enter 5,000 gals at the top of the calculator for pool size, then as you stated above, I entered a starting (NOW) number of 7, and a TARGET of 7.5. The calculator told me to add 15 oz (by weight) or 13 oz (by volume) of washing soda or soda ash. Now it appears you are seeing a color that appears to shoot-up too high again correct? If so, everything you've done so far seems to be in-line with PH increase procedures. Just curious, but is there any chance that perhaps your listed pool (gallon) size is not correct? That would influence what actually happens as well. Also, have you had any questions or concerns about the method of testing PH with your K-2006 to rule-out a testing error or inconsistency? Just throwing a few ideas out there.

 

[liulady]

Thank you so much for your replies. I'm at work right now and can't run tests, but I'll definitely post a full set of numbers when I get home this evening. Hopefully, the PH will have dropped a bit. But, if not I will go get some Muratic Acid. Thanks for the info. on what to get so that I can avoid going back to the pool store!

Texas Splash, yes, you stated that exactly. I knew that my TA was low as well as my PH. My TA was around 60. So, I chose to work on the PH first and added the 13 oz of Soda Ash as directed by Pool Math. I am reasonably confident that I performed the PH test correctly as it is a pretty straightforward test. As far as my gallon count being off...I guess that is possible, but the pool IS filled to the brim. Anyone else out there with my pool measurements who thinks that 5K is not a correct gallon count? Just curious...

Thanks again! I am using only 8.25% bleach as my chlorine (learned my lesson about dichlor granules!), so I guess I do need to get used to my PH moving around more than it did before. In the past, my PH was very steady at between 7.4 and 7.8 so I never had to mess with it. But, the side effects of the high CYA are definitely not worth a solid PH level!

 

[liulady]

Oops...just reread my post and realized that the measurements of my pool are not listed in my signature. My pool is the 16X48 round Intex Pool. It is listed in the manual as 5K gallons.

 

[Pool Tool]

Assuming 16' Diameter Round pool completely full (48" of water) I come up with 6,015 gallons. Volume of same pool with 42" of water = 5265 gallons; 45" of water = 5640 gallons. I would expect you to keep around 45" so I would use 5600 gallons in Pool Math.

One other thing is that I would make sure to rinse the tube(s) very well while testing. It doesn't take much residual water/reagents to effect the tests. Before you fill the vial, rinse it in the pool 3 or 4 times then fill it up.

Edit - Thanks for updating your signature, I found the dimensions in your first post but didn't know if pool was round or not.

 

[liulady]

Alrighty...got home from work and went straight out to test the pool. We are in the middle of a heat wave here and the temp is 103 out there. I'm sure the water is in the 80s.

Here is the full picture:

FC - 0 (Oops! I dosed it up to 7 ppm last night, but that clearly wasn't enough to combat the heat and people swimming today. I'm learning that I need to compensate with more than the usual for these days. I dosed it back up to what should be 8 ppm)
CC - 0
CYA - 60
PH - 8+
TA - 80

So, the PH is still very high. The test only reads to 8 and I'm sure it is a bit higher than that. But, with the lower range TA I'm really reluctant to add Muratic Acid. Should I rush right out and lower the PH? Wouldn't that also bring my TA down? I'm still really confused as to why the 13 oz of Soda Ash took the PH SO high. The only other thing I've added to my pool is enough liquid stabilizer to bring it up to the 60 CYA and then 8.25% bleach to maintain the chlorine.

 

[pooldv]

Your TA is fine. Add muriatic acid to lower PH to 7.5 asap. It is important to maintain ph between 7.2 and 7.8.

It is fine to take chlorine up to 10 or more so that it does not drop below minimum of 5. When chlorine drops below minimum the pool is not properly sanitized and algae will grow. Chlorine CYA Chart. It is safe to swim when chlorine is above minimum and below shock level for your CYA.

 

[liulady]

That sounds like a plan. I'll get MA and lower my PH. Hopefully, that won't affect my TA too much?

And, I had just come to the same conclusion with my Chlorine...still figuring out how fast it drops. I think I'll stick with 10 ppm to avoid dropping to zero again on the next scorcher day!

Thanks again!

 

[Pool Tool]

TA is important but having it be a touch low is not detrimental to you or your pool. Having the ph out of range can severely and quickly impact both you and your pool equipment.

I wouldn't worry about why the 13 oz effected it so dramatically. I think there were other factors involved that probably won't present themselves again. Keep treating you pool per PoolMath to get within the suggested levels. Later if you see dramatic swings not predicted by PoolMath then we can address those. Until then get your ph to around 7.5 like dv said (you probably already have) then manage your FC levels. You will find a sweet spot soon enough.