Can't get pH up and keep it up

[theSmurfette]

pH 7.0
FC 0
CC 2.0
TA 70
CH 50 -- but I don't believe this number because our area has hard water
(and when I was using an HTH 6-way test a few years back, the total hardness was so high that I had difficulty with the test)
CYA 35

I just added 121 oz of 8.25% bleach tonight. Pump is on a timer, set to run on low for 6 hours at night. It's maybe 2 hours into its cycle right now. Up until today, my CC was no more than 0.5. What do I need to do to get my CC back down?

I've added over 6 lbs of baking soda over the last 1 1/2 weeks trying to get the alkalinity up. I believe I need to add more to get it to TFP recommended value of 100. Once I get that up, will my pH stabilize more? Or is that the battle I will fight all the time? I can get it up to 7.4 and then it will go back down to 7.0. It tends to hover around 7.0-7.2 most days without changing anything CYA is a little low still; added 4 lbs of CYA a week ago. I tested CYA about 4 days ago and I rechecked it tonight, it has not changed. Will it continue to rise even though it's already been a week since it was added? I also have some old pucks that I could float in the pool if that could help get the CYA up some more.

Suggestions??

 

[chem geek]

Where do you see that the TFP recommended value is 100? The Pool School Recommended Levels for a non-SWG pools is 70-90+. Your 70 ppm for your vinyl pool should be fine. If you need to raise the pH, try aerating the water or using some 20 Mule Team Borax.

Your CC may be from having your FC get to 0. When you add CYA, the pH will drop, but it should not normally be dropping once you stop adding the CYA if you are not using acidic sources of chlorine. If you are using Trichlor pucks then they are acidic. If you use bleach or chlorinating liquid then you shouldn't be finding the pH dropping. If you use old Trichlor pucks to get your CYA up more, which you probably should since you seem to be losing too much FC too quickly in sunlight, then you can raise the TA some probably to 80 or 90 but I wouldn't go higher just yet. The baking soda won't raise the pH that much -- you need to either aerate the water or use 20 Mule Team Borax for that (or you could use pH Up -- sodium carbonate or washing soda product but that also raises the TA).

For the CH test are you using a 10 ml water sample and seeing it turn from red to blue in only 2 drops or are you using a 25 ml water sample and seeing it turn from red to blue in 5 drops?

 

[theSmurfette]

Where do you see that the TFP recommended value is 100? The Pool School Recommended Levels for a non-SWG pools is 70-90+. Your 70 ppm for your vinyl pool should be fine. If you need to raise the pH, try aerating the water or using some 20 Mule Team Borax.

That's what the default value was on PoolMath. I noticed that was higher than the recommended levels but thought someone else knew better than me.

Your CC may be from having your FC get to 0. When you add CYA, the pH will drop, but it should not normally be dropping once you stop adding the CYA if you are not using acidic sources of chlorine. If you are using Trichlor pucks then they are acidic. If you use bleach or chlorinating liquid then you shouldn't be finding the pH dropping.

We dissolved the CYA by hand on 7/4. We have not added anymore since then. I have not used tricolor pucks since filling when my kids were playing in the pool when it was filling. I do have them if that will help get the CYA up more.

If you use old Trichlor pucks to get your CYA up more, which you probably should since you seem to be losing too much FC too quickly in sunlight, then you can raise the TA some probably to 80 or 90 but I wouldn't go higher just yet. The baking soda won't raise the pH that much -- you need to either aerate the water or use 20 Mule Team Borax for that (or you could use pH Up -- sodium carbonate or washing soda product but that also raises the TA).

I tested this morning. This was after running the pump for 6 hours last night and adding 121 oz of 8.25% bleach. I have a fountain that I was planning to install to help lower water temperature later this summer. Would that help keep my pH up better than just running the pump?

pH 7.4
FC 6.0
CC 0
TA 70

For the CH test are you using a 10 ml water sample and seeing it turn from red to blue in only 2 drops or are you using a 25 ml water sample and seeing it turn from red to blue in 5 drops?

My sample has never been red. It starts out at purple. I remember reading somewhere that I needed to add more of one reagent to counteract something in my water but I can't remember where I read that. It is 50ppm using either the 10mL or 25 mL test.


Thanks for the help!

 

[chem geek]

In the Suggested Goals section at the bottom of PoolMath you need to change "Use suggested goal levels from:" to "troublefreepool.com".

So your CC now went away, possibly from the chlorine oxidizing it so that's good.

You can use a fountain for raising the pH, but that would imply your pH normally getting lowered by acidic sources such as Trichlor. So over time the TA will drop and you'll have to manually add baking soda. If you were using only chlorinating or bleach and weren't adding any acidic chemicals to the water, then the pH should not be dropping.

Yes for the CH test you can add titrant drops (R-0012) at the beginning of the test before adding the indicator dye and calcium buffer. Just count those titrant drops in your total. Test your tap water to see if it measures high in CH given your high water hardness. Do you have a water quality report from your water district that confirms that your water is hard?