PH keeps increasing

[39lasalle]

Iam using the bleach method..... for some reason my PH keeps going up past the 8.0 mark on the Taylor test kit.  Yesterday, I adjusted down to normal levels and this morning I am up to the 8.0 again.

Everything else is near perfect (if there is such a thing)

Any thoughts?

Thanks

39

[Hottubguy]

Bleach has a ph of close  to 13. I suspect that is the main reason why your ph keeps rising

[bud16415]

How much bleach are you using?

[39lasalle]

How much bleach are you using?

About 4 to 6 oz. depending on how long and if it just me or both of us in the tub.

[bud16415]

I start out with Dichlor and then switch to bleach once my stabilizer reaches the good zone. I haven’t had much problems with PH climbing like that and if it gets a little high I adjust it down and it stays there. The fact you adjusted yours and then it jumped back up over night without adding more bleach makes me think it is not the bleach even though bleach has high PH.

Others may have some ideas. 

[Tman122]

How much bleach are you using?

About 4 to 6 oz. depending on how long and if it just me or both of us in the tub.

How is your Alk? This helps stabilize your PH.

[The Wizard of Spas]

This is unlikely but something that should be pointed out:  When chlorine sanitizes (becomes hypochlorus acid) it is a high pH event.  So if you have a high amount of chlorine in your water, or if you're testing too soon after adding your sanitizer, it could be a false-positive.  This is very similar to what Hottubguy mentioned and he's likely the one with the most relevant answer to your question but I thought I'd add this too.

[39lasalle]

OK, I mostly use tub from about 7 PM to 8 PM nightly. I usually test first thing in the morning just to see where I am at.  I will try to remember to test this evening before use and if weather holds up.  I just wasn't sure if that was normal, sounds like it is, I am just maybe testing too soon!

Thanks

39

[bud16415]

It could be that, I have a 400 gallon tub the 2 of us use it just about like you do and I add a similar amount of bleach after usage. The few times I tested the next morning I never saw a jump like that, but 99% of the time I test it when I get home from work. I like to find it down around 1-2PPM. Based on what it was I may or may not add some bleach after we get out. If I know we are not going to use it for a few days that is when I shock it if it needs it. The only difference I see in what we are doing is I start off with dichlor. What does your stabilizer normally measure?   

[castletonia]

One other thing to consider is that when you run your jets, you are basically aerating the water which causes the pH to rise.  If your total alkalinity is out of range, the pH will fluctuate more.  And, as others have said, bleach has a pH of 13.

[mpkelley20]

The way I understand it is that bleach will initially raise your PH but, as it burns off, your PH will come back down to similar starting levels.  Depending on what brand you are using and what the specific PH is of that brand, you might get a "net" positive on your overall PH over time.  Shouldn't be a quick thing though.  If you are testing shortly after adding bleach, you will get that high PH reading. 

The "fix" for dealing with a net positive is to lower your Total Alkalinity a bit from what I understand.  I keep mine around 55-60 range which seems to hold PH much more stable. 

As others have stated, aeration from air jets running can cause PH to rise as well as having a TA that is our of whack. 

[wmccall]

This is unlikely but something that should be pointed out:  When chlorine sanitizes (becomes hypochlorus acid) it is a high pH event.  So if you have a high amount of chlorine in your water, or if you're testing too soon after adding your sanitizer, it could be a false-positive.  This is very similar to what Hottubguy mentioned and he's likely the one with the most relevant answer to your question but I thought I'd add this too.

This is a good point, my knowledge is less than most on this subject, but when I make a change on PH, I wait 2 days to check again.

[39lasalle]

This is unlikely but something that should be pointed out:  When chlorine sanitizes (becomes hypochlorus acid) it is a high pH event.  So if you have a high amount of chlorine in your water, or if you're testing too soon after adding your sanitizer, it could be a false-positive.  This is very similar to what Hottubguy mentioned and he's likely the one with the most relevant answer to your question but I thought I'd add this too.

This is a good point, my knowledge is less than most on this subject, but when I make a change on PH, I wait 2 days to check again.

I see you saying 60 for the Alk..... I think the book is saying over 100... maybe I will reduce a see what happens...
Thanks

[dlleno]

there's little reason to target a specific TA value - the goal is pH control and the most common mistake I've seen is setting TA at some arbitrary level promoted by a store or a book.  the better way is to use dry acid to control pH rise, and this will naturally bring TA down. high TA values encourage pH drift. 

another note to make is that if you are using the "dichlor then switch to bleach" method, this very often requires a pH buffer such as boric acid. to control pH drift.    Personally i found that letting TA drop to 40ppm or so, even 30, is an effective way to control pH drift, but again the point is not to target a specific TA value the point is to control pH.  Remember too that an acrylic spa can operate just fine with a slightly negative saturation index, which will nearly always occur if TA is that low.