Something is wrong. High TA but low PH

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amati5

Well-known member
Sep 13, 2011
233
So Cal
The TF-50 is on the way but while waiting, I thought I should ask.

Back in early March, my SWG pool showed zero FC and PH (both showed clear water) so I took the water to the pool store. Results showed:

TA = 140
CH = 600
CYA= 40
FC = low
PH = normal (my test showed very low, clear water)

I waited for the rain and drained about 1/3 of the pool. Added CYA and Algaecide and waited for a week and brought it back to the pool store twice to test.

TA = consistently high
CH = down to 400 and then back 560 (Not sure why it came back high though water is very hard in my area, or they messed up the test)
CYA = 100
FC =low (consistent with my test)
PH = normal (again, my test showed very low)

This past Sat, I cleaned the filter and super chlorinated the pool and the next day I had good FC but still low in PH (a little pink vs. clear). 6-7 hrs later, about 7PM, my FC dropped to below normal. I have several questions:

-Why the pool store's PH test consistently showed normal vs very low in mine.
-Would the high CYA make my FC drop that quick? I know it makes the FC less efficient but am not sure if it actually lower the level. The range from the pool store show CYA to be between 60-99 (probably based on SWG pool and being sunny CA) so 100 isn't that bad, correct? I would hate to drain the pool in the middle of the drought so may be I should wait until it lower itself? I always have to add every spring.
-My TA is high, why PH is low? Because of low FC?
-Lastly, To add CYA, I put it in a net bag, dipped in the skimmer with pump running and use my hand to break them into fine powder until everything is gone. Is it an OK method to speed up the result?


Thanks for your input.
 
How old is your pH test? Where is it stored? What test kit is it? I have never seen the pH test being clear ... that is not right.

- I do not trust your pH test ... should have ordered the TF-100 ;)
- High CYA would make the FC drop more slowly as it is better protected from the sun. It does not make the chlorine "less effective" exactly, that is an over-simplification. Pool stores are horrible at testing the CYA and their ranges are worthless as well. I think you are heading toward needed to replace water ... lets see what your kit says.
- What does "high TA" mean ... wait for your kit. FC has nothing to do with TA
- Likely the method you described is ok, it is probably not fully dissolved when it gets out of the net and just gets captured in the filter ... just wait a week before you test for the new CYA level.
 
That was my first thought about my PH test solution. Since it requires only one drop per test it's old and it's stored in a cabinet outside in the shade 100%. It's just a generic solution I don't remember where I bought from. But since it did change to a little pink after super chlorinating, I assumed it still works.

This is the first time I ordered a big test kit so I just want to see how it works first.

From what I've been reading, too high CYA isn't good for Chlorine to fight bacteria, is it?

Total Alkalinity = 140. If the CYA isn't fully dissolved I will be in more trouble as and it's alreay at 100, lol....is 100 really that bad for swg pool and in the really sunny area?

Thx
 
At high FC levels, the pH test do not work correctly. You test is bad. Get a Taylor pH/OTO test kit to add to your TF-50.

If you keep the same FC / CYA ratio, then it does not matter how high the CYA is. If you do not raise the FC level when the CYA level rises, then you will run into problems. See the FC/CYA Chart

Having high CYA will better protect the FC from the sun, so the SWG would have to work less to maintain adequate FC levels. The issues with high CYA pop up if you need to SLAM as the FC levels get VERY high. Also, high CYA requires higher FC and when the FC > 10ppm, the pH test is invalid.
 
I am confused! My FC has been low, never too high. It's only went to 3-6 (which is ok for SWG pool, accordring to the chart) after I supper chlorinate the pool (which dropped quickly afterward) and PH was still low.

I guess I'll pump up the Aquarite output and get a new PH test and see. As long as I don't have to drain the water I am happy.
 
I do not follow the last post.

If you need to quickly raise the FC, then use bleach, not the SWG. The SWG is better at maintain FC not raising it.

The MINIMUM the FC should ever be with a SWG pool is 4.5% of the CYA level. So assuming your CYA is 100ppm, your FC should NEVER be below 4.5ppm ... which means I would try to target around 6ppm
 
I can't quickly raise the FC by super chlorinate the Aquarite ? and don't I have to increase the output to maintain the required higher chlorine since CYA is high? I also thought bleach was never a good idea to chlorinate the pool. I think I am missing something.
 
He he...I am more of a seasonal member with the "senior" tittle based on the date I registered. However, I read about pool stuff "as needed" over the past 15 yrs and I remember reading (not from here) chlorine in bleach is not the same and I have always thought it's has been know this way. I read Pool School but to be honest, I haven't got much problem with my pool in the last 15 yrs so again, I only check again "as needed". I only go the pool store about once or twice a year just to test the CYA and once it's good, I am set for the rest of the year. But I learned a lot from here, including never trust the pool store with their data so I am ordering my first test kit. I also learn from experience that as simple as it sounds, I always learn something new and I learned from you today that higher CYA needs higher FC, beside using bleach to boost FC. Thank you.
 
Alright. The kit came home and I did the test.

CYA=75 (pool store's=100)
TA=150 (consistent with pool store's)
FC=3.5 (was about 6 after adding bleach last week)
PH= Will get a fresh one and test
And guess this, CH=1000 (first sight of blue. The first time it was 1500 because I wanted to see deeper blue, wasn't sure how dark it should be). Waterhardness in my area is 14-25 grains/gallon, very hard.


I guess I need to add a little more CYA to bring it up to 80 (SWG) but am clueless what to do about CH. I've already drained 1/3.
 

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On the CH test, you are not looking for any specific blue. You add drops until it turns to anything in the blue family, then add additional drops until the last drop doesn't change the color any further. The final drop, which doesn't change the color, doesn't count. Generally first blue to final blue is 0 to 2 drops.

CH around 1,000 is very close to the highest you can possibly manage CH without having scaling. Worse, CH tends to go up over the course of the season, as topping off evaporation tends to increase the CH level.

Do a CH test on your fill water to find out how much of an ongoing issue CH is going to be.

By the by, with high CH levels you are going to want to bring down your TA level.
 
First I didn't believe the test I did on my own until I did some reading that most of pools in the southwest region have this problem because of the hard water. My local pool stores never had this high result for my water in the past 14 yrs. Makes me wonder if they were hiding something and why did they tell me to drain. They must know how hard the water here. I am surprised not seeing complaints on the net from pool owners in this area. Testing CH on the fill water is a good idea. Wish I'd done that before draining, possible saving tons of water.

Another story from the pool store: Went to pick up a refill for PH test. While checking out, I just decided to ask if it needs just 1 drop (Been doing that). The guy said 5 drops. I asked if he was sure and he asked me if I use the small or large test . I told him the small one and pointed to small test kit on counter. He turned to another senior person to confirm and the senior person said, yup 5 drops. I came home and got on here find out I just need 1 drop for R0004 which they sold me. The result looked much more reasonable.

I will leave my CYA alone for now and try to bring down TA.

Thx
 
You would get slightly better results by using the correct pH reagent for your tube ... Taylor themselves claim that R0004 and R0014 are not interchangeable (although I do not know if that statement takes into account using a different number of drops). You could end up with more chlorine interference since you are only adding 1 drop ...
 
I'll try to exchange for the R0014 but I'll try 5 drops first to see what it look like. I was thinking the result would look very high in PH. By the way, to aerate, will it work If I divert the returned water into my spa and let it spills over back to the pool?

thx
 
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