Help. Can't stabilize pH with normal alkalinity

[boomrabbitt]

2 wks ago I used yellow gone to kill mustard algae. Follow directions to the letter. Now it is coming back. I just ordered a Taylor TF100 so I can follow the instructions found here. Should be here in a few days. But right now I have a pH problem. It drifts upward. I raised alk to 120 so I could drop the pH without dropping alk to low. I have used 2 gallons of muriatic acid over 4 days. PH has been quite resistant to drop. pH was 7.3 yesterday.
Today:
Cl 4
pH 7.7
Alk 90
CYA 30
calcium 220
Temp 87

 

[mknauss]

Welcome to the forum -- there may be some issues with that 'yellow gone' but more on that later.

Normally you keep adding MA to keep your pH below 7.8 and once your TA gets to a spot that it balances your pH stops rising. The caveat to that is if you have high TA fill water, I do, at 130, so I will always use MA.

Do you still have the bottle for the 'yellow gone'? What are the ingredients? Need to know as there may be issues with adding that.

Take care.

 

[boomrabbitt]

It doesn't list the ingredients. But there is a thread on here about it. There are a few brand names, yellow out, yellow rid, yellow gone etc. I read that it could stay in the pool for 7 to 10 days if it hadn't used up all the chlorine that goes with it. But I was fine for a week after this was done.
I have never had a problem with alkalinity. I use cal hypo and trichlor tabs. They pretty much balance each other out regarding pH. The alkalinity usually stays 90-100. The trouble started after the yellow gone. You use a lot of shock with it. Of course my pH went through the roof. In trying to correct that after the algae kill, I now have the current problem

Water is clear btw

 

[mknauss]

You are throwing a number of items that effect pH, cal hypo, trichlor, baking soda, potions, etc. May take some time to balance. I would just keep the pH below 7.8 and see if it stabilizes.

As long as the yellow stuff was not sodium bromide. That creates issues. Should not have to use it anyway if you keep your chlorine within the chlorine /CYA chart parameters.

Take care.

 

[AftonJeeper]

If it is this stuff from home depot it is sold as an algaecide and it's active ingredient is Disodium salt of Ethylenediaminetetraacetic Acid Dihydrated Ammonium Sulfate. Please don't ask me what that is.

Personally I'd wait for the test kit to show up and stay focused on keeping the pH between 7.8 and 7.2 and you FC over 4. Some pools live at a pH of 7.8. My TA is 170 last I checked and my pH hardly moves off of 7.5 when the pool is not in use, each pool is different.

 

[boomrabbitt]

I would love to keep the pH below 7.8. That's my problem. I simply cannot do it. It will be perfect in the afternoon, the next morning it's up again. After adding nothing.
The mistake I made was using the yellow gone algicide. I had to adjust pH and alkalinity upward prior to using it and just after. That's when things went haywire. And the mustard algae came back two weeks later. Talk about a colossal waste of time and money. Just hope my test kit gets here before the pool goes totally green. Thanks for everybody's replies. I will consider anybody's input.

 

[boomrabbitt]

Since my TF – 100 kit is in the mail, I didn't want to wait to tackle the mustard algae. It would be terrible by next week. So I am trying to SLAM with a regular test kit that only goes to FC of 5. I'm using the dilution method. 5mL pool water 20mL tap water (well water). Then multiply the result times 5. I used a couple drops of sodium thiosulfate to neutralize the chlorine in my pH and alkalinity tests since they are not accurate at high chlorine levels. Or so I understand from the forum
Last night I raised CL 20. Brushed.
This morning:
CL 15
pH 8
Alk 80
CYA 30
Cal 220
Cloudy water after brushing.
I added cal hypo to 23. Vacuumed. Brushed. Added MA for pH. Added NaBicarb for Alk. A few hours in between each addition.
Now:
Cl 20
pH 7.6
Alk 110
Clear water
I know that's a lot in one day. But I needed to get the pH down so the chlorine will work. As a result, the alkalinity would surely drop. Everything looks good now. Hopefully it will still look good in the morning .
Please let me know if anybody sees something wrong with my thought process.
Thanks so much!

 

[Catanzaro]

boomrabbitt:

Welcome to TFP. If you are adding chlorine and then testing for PH, you will have high PH. PH increases with additions and then as the chlorine is burned off, your PH will drift right back to normal. Your high TA could also be a major factor in rising PH. I had to lower mine from 130 to 70-80 before my PH stabilized. Although, I have rotating return jets.

Do you have a waterfall or any other type of aeration devices. These along with high TA and liquid chlorine will definitely keep your PH on the rise.

 

[boomrabbitt]

No I do not have a waterfall or any other aeration device.
I have had to raise the alkalinity a bit when using MA for pH lately. I raised Alk last week because I had so far to go in lowering pH. It only rose to 120 then but maybe that was too much for my pool. I usually put a little MA after Cal hypo because it raises pH. Have never had a problem with alkalinity dropping I assume because my fill water is very alkaline and we had a leak. Now that it's fixed, I don't have alkaline water running in like we used to.
Anyway, I raised alkalinity a bit today because every time I shocked the pool, I will be using MA.
Also, when I add chlorine of course pH rises but the chlorine burns off like it normally does, but the pH remains high. Other folks say there's returns to normal after chlorine drops. I wonder why mine doesn't
Curious to see how it looks in the morning.

 

[mknauss]

Why not take the cal-hypo out of the loop on this? Use liquid chlorine.

Take care.

 

[boomrabbitt]

Does Cal hypo raise the pH more than liquid chlorine?

 

[JamesW]

Stop adding bicarb. Forget about trying to get to a specific TA.

If your pH keeps drifting too high, your TA is too high. If your pH keeps going too low, your TA is too low.

When your pH is stable, the TA is correct.

Try a pH of 7.8 and a TA of 60.

 

[boomrabbitt]

Oh well that would be easier. Haha.
The only reason I worry about the high pH is cuz I've read that the chlorine is nearly ineffective at 7.8.

 

[JamesW]

Chlorine is fine at a pH of 7.8.

Keep the CYA correct and your chlorine at 10 % of CYA.

 

[mknauss]

Pool Water Chemistry

Go to the second post on this sticky thread. It discusses the relationship between pH, Chlorine, and CYA

Essentially, the presence of CYA moderates the effect of pH on chlorine.

Take care.

 

[boomrabbitt]

Today's chemistry
Cl 17
pH 8
Alk 110

I checked a couple threads here just to make sure I was doing the tests correctly. All is well there. I even checked my thiosulfate to make sure it eliminates chlorine from pH and alkalinity samples. Even when the alkalinity was 80 and chlorine was 4, the pH bounced way up overnight.
So I should lower the alkalinity to below 80?

 

[mknauss]

Vibrant pink. A method recommended for all the tests is to add drops until there is no change in color and then subtract your last drop.

Take care.

 

[AftonJeeper]

When your chlorine level is over 10ppm you cannot test pH accurately, it will always read higher than it is.

 

[boomrabbitt]

I neutralized the chlorine with sodium thiosulfate drops before testing. Is it still in accurate after doing that?

 

[JamesW]

Try TA at 60.