Lowering pH?

[KleanKiddiePool]

I'm in the process of opening my 2500 gal Intex.
Our tap water is naturally alkaline.

I've been using bleach with increments of dichlor.

The estimated CYA added from the dichlor is approx 35-40 ppm. So, I'm probably done adding the dichlor.


pH = 7.8
TA = 240


Do I need to decrease my pH to improve effectiveness of chlorine?

I've got some Sodium Bisulfate. I've never used it or muriatic acid.

 

[chem geek]

The high TA will make the pH tend to rise so you'll probably have to lower it through a lot of acid addition and aeration (see the Pool School) until your pH tends to become more stable.

 

[duraleigh]

Richard is, of course, correct, but I might just wait on it a little bit and see where your pH goes.

7.8 is at the upper limit of acceptable but acceptable nevertheless.

Through some of the vagaries of pool water chemistry, it may not go above that. Probably will do just like Richard said but there's no harm in just testing and watching for a while.

 

[JasonLion]

There is no need to lower PH because of chlorine effectiveness. Chlorine is significantly less effective at high PH only when there isn't any CYA. Once there is CYA in the water the change in effectiveness due to PH mostly goes away, and the remaining effect can be ignored.

I would lower PH to 7.2 just to bring the TA down a bit. After that, watch the PH for a while to see if it goes up quickly or not. If it goes up quickly you will want to lower the TA further. But if PH only drifts slowly then it is simpler to wait for the PH to get back to 7.8 and adjust it down again then.

 

[KleanKiddiePool]

Thanks for the explanations.



I'm not crazy about handling acid. Concerned about mixing/ safety etc.


For my pool size it would require 3.75 ounces of dry acid.

Sodium Bisulfate label says to add acid to a bucket of water first.

What should the size of this bucket be?
Label says one gallon or larger.



Any thoughts on the best/safest bucket size for dilution?

From dilution standpoint the larger the bucket the better.
My concerns, for instance with a 5 gallon bucket, is that it is difficult to handle and more likely to splash than a one gallon bucket.
A 1 gallon will be much easier to handle.

 

[Richard320]

First, a question, then some answers.

Do you have a good test kit? Test strips don't count, nor does letting the pool store do it. It's essential, especially given the small volume of your pool. A mismeasurement can lead to overdosing, and then trying to compensate, leading to a vicious circle.

For mixing, whatever you have handy will work, as long as it's plastic. Before I was sure what finish I had, I bought a tub of dry acid. I use the empty bucket for my mixing. I guess its a gallon and a half, maybe two gallons. Small enough to handle easily.

If all you have is an empty 5 gallon bucket, use that, just don't fill it all the way.

Dry acid does contain sulfur. I don't know the exact conditions chemically to cause it, but from time to time I would get a sulfur smell. Could have been from the ornamental garlic, who knows? I prefer to not put any more in my pool; muriatic acid is cheaper anyway.

My technique: carry bucket, measuring cup, and jug of acid to poolside. Dip acid jug in pool and swish it around, in case there's any spillage in the crate stuck to the jug. If there is, you'll get a nice ring on the deck when you set it down. Ask me how I know. Anyway, rinsed jug gets set down. I scoop out 3/4 of a bucket of pool water and set it down. Then I uncap the jug, and pour the acid into the cup over the bucket, in case of spills. Cup gets dumped, then rinsed in the pool. Jug gets capped. Then bucket gets lifted, held far over the side, and poured in near a return. Then bucket gets rinsed in the pool a few times. Then it all gets put away. It probably took longer to type it than do it.

Millions of pool owners use muriatic acid, and you seldom hear of any injuries. Mysterious pinholes in clothes are common.

Always add chemical to water, not the other way around.

 

[KleanKiddiePool]

OMG I'm so glad you asked about my test kit.

I use the DPD test kit with liquid reagents: R0001-R0002-R0003 for chlorine. The testing tube ranges from 0-5 and color turns pinkish red. My results were ranging from 4-5 (Or so I thought!!!)


Your question prompted me to read the Extended Test Kit Sticky extended-test-kit-directions-t25081.html

OMG!!! From sticky:

This test normally reads from 0 to 5. You can test from 0 to 10 by using 4.5 ml of pool water and 4.5 ml of chlorine free water (typically distilled water) and multiplying the result by two. You can also test from 0 to 20 by using 1.8 ml of pool water and 7.2 ml of chlorine free water (typically distilled water) and multiplying the result by five.

I never knew this before.

So, this is exactly what I did. My FC was 20!!!
At this level I can't tell what the TC is, but I grabbed an OTO test kit and it turned burnt orange!


Now I know why my TA was so high!! OMG

Thank you! Thank you! Thank you!

Based on this "chlorine overload", I don't think I'm going to worry about adding acid at the moment!!

I will be testing the FC/TC using my newfound knowledge over the next few days.



As for the CYA I will need to take a sample to Leslies. It was 0 two weeks ago. I've been very conservative about adding CYA.

Once again. Thank you! Thank you! Thank you!

I learn so much from TFP!