Question re Balancing Water

[Quickbeam]

I just recently did my first water change and would like to get some advice re balancing my water.

My numbers are as follows:

PH - 7.6

TA - 30

CH - 130

I know that my TA is low, but it needs to be at 30 for my PH to stay stable during aeration. My TA was also at 30 during my initial fill. Given the numbers above, my Saturation Index is just under -0.5 (our hot tub is at 101 degrees), which puts my water out of balance. I could raise my PH to 7.8 which would bring me in balance, but I’m wondering if I really need to, as I am thinking a PH of 7.6 is a pretty good number. I remember in a previous post that Chemgeek had said that with an acrylic shell tub with no exposed plaster or grout there is no real need for having the CSI be near zero. So my real question is, should I leave my PH at 7.6, or should I add some borax and try and bring the PH up to 7.8?

[Jacuzzi Jim]

 Nothing wrong with what your doing, but I think your over thinking it..    Bring the alk up a bit and call it good, give it a few days and see where it goes..   


   It's more me than you, so please don't take that wrong..

[chem geek]

You don't need to worry about the saturation index if your spa is acrylic and you have no plaster or grout exposed to the water.  Also, it would be better to have a higher pH target such as 7.8 with a higher TA target (40 or 50) if you can still have the pH be reasonably stable there (you can see from this link that the over-carbonation should be fairly similar).  With a low TA you have to be VERY careful not to use net acidic chemicals in the water that would use up the TA or else your pH will crash.

Are you using 50 ppm borates (usually from boric acid)?  That will provide more pH buffering given that your TA is low.  It especially helps slow down the rate of pH rise.  You don't want to misjudge your aeration and end up with the pH very high which can then cause calcium carbonate scaling (though with your low TA the risk for that is fairly low).

I presume you are using the Dichlor-then-bleach method, correct?  Keep in mind that Dichlor is net acidic and for every 10 ppm FC it will lower the TA (after chlorine usage/consumption) by 3.5 ppm.  So if you use Dichlor for 40 ppm to add 36 ppm CYA to the water, then the TA will drop by 14.1 ppm.  That's another reason to start out a little higher in TA.

[Quickbeam]

Thanks Jacuzzi Jim and Chemgeek for the responses. I have found with a TA any greater than 30 my PH shoots up with any significant aeration in the tub. Unless I’m missing something, I don’t think I can have my TA any higher than 30. As for borates, yes, I am using 50 ppm from boric acid. As for my sanitizer, I’m using hydrogen peroxide. I know that’s not the normal way to sanitize but so far we really like it.

[chem geek]

OK that's fine.  Hydrogen peroxide breaks down into water and oxygen gas and when reacting with nitrogenous compounds produces water and nitrogen gas so is pH neutral.  For proper disinfection, the hydrogen peroxide level should be around 100 ppm but that is a level some people find to be irritating.  Hydrogen peroxide is not an EPA-approved disinfectant, but it is approved by the APVMA in Australia where you can see this label requiring (100/850)*598 = 70 mg/L to (250/1500)*598 = 100 mg/L and this label stating a minimum 100 ppm level to be maintained and this label (for pools) requiring 100 ppm and never going below 40 ppm.

[Quickbeam]

Thanks Chemgeek,

So do you think I should leave the PH at 7.6 or should I try bumping it up to 7.8, or does it not matter?

[chem geek]

If your pH is stable at 7.6 you can leave it there.  Though it doesn't matter, you might as well be closer to the 7.5 midpoint of the pH test giving you ample warning if the pH drifts from there too much.

[Quickbeam]

Thanks Chemgeek!

[Budule]

I don't have my tub yet but I ask the Jacuzzi dealer about different sanitizers and when I mentioned hydrogen peroxide he told me it would void my warranty ,  Jacuzzi claims (don't know if its true or not but its their tub till the warrant runs out ) that hydrogen peroxide dries out the seals and causes leaks down the road after time.....

[Jacuzzi Jim]

I don't have my tub yet but I ask the Jacuzzi dealer about different sanitizers and when I mentioned hydrogen peroxide he told me it would void my warranty ,  Jacuzzi claims (don't know if its true or not but its their tub till the warrant runs out ) that hydrogen peroxide dries out the seals and causes leaks down the road after time.....

  Hog wash, dealer can sell what they want as far as chems.   Might be in the small print somewhere I have just never read it.  But they do use the same gaskets or made of the same material anyway as everybody else so it would probably be fine.   
    Least in my book I would cover it and not look for an excuse as to why something failed and push it back to the consumer for a reason not to cover it.

 All that said I would not use hydrogen peroxide as a sanitizer.   

[Budule]

I don't have my tub yet but I ask the Jacuzzi dealer about different sanitizers and when I mentioned hydrogen peroxide he told me it would void my warranty ,  Jacuzzi claims (don't know if its true or not but its their tub till the warrant runs out ) that hydrogen peroxide dries out the seals and causes leaks down the road after time.....

  Hog wash, dealer can sell what they want as far as chems.   Might be in the small print somewhere I have just never read it.  But they do use the same gaskets or made of the same material anyway as everybody else so it would probably be fine.   
    Least in my book I would cover it and not look for an excuse as to why something failed and push it back to the consumer for a reason not to cover it.

 All that said I would not use hydrogen peroxide as a sanitizer.   

He was just telling me Jacuzzis position on the matter , knowing this guy , he would cover it if I dumped gasoline in there ......his concern was problems down the road AFTER the warranty period if leaks start poping up......I wasn't going that route anyway even though its probably fine......

[Quickbeam]

We just recently purchased a Jacuzzi 345 and before we bought I specifically asked the dealer about warranty coverage. He went to Jacuzzi and came back and told us that Jacuzzi would discourage the use of hydrogen peroxide but if we did use it our warranty would not be affected. It was only on that basis that we purchased from Jacuzzi, as before we purchased any tub we had our mind made up we were going to use hydrogen peroxide.

[chem geek]

As for hydrogen peroxide wear on hot tub components, see this post, this post, and these posts.  Also, this manual ("Please avoid using any spa chemicals that contain Hydrogen Peroxide. Hydrogen Peroxide based spa chemicals have been found to react adversely with the materials used to produce these components.") and this manual ("Alps Spas strongly discourages the use of chemicals that contain Hydrogen Peroxide. Hydrogen peroxide will eventually cause the light body and lenses (used on all spas) to become brittle and crack.").

[Budule]

As for hydrogen peroxide wear on hot tub components, see this post, this post, and these posts.  Also, this manual ("Please avoid using any spa chemicals that contain Hydrogen Peroxide. Hydrogen Peroxide based spa chemicals have been found to react adversely with the materials used to produce these components.") and this manual ("Alps Spas strongly discourages the use of chemicals that contain Hydrogen Peroxide. Hydrogen peroxide will eventually cause the light body and lenses (used on all spas) to become brittle and crack.").

glad I read those , but I don't think I was going to try it anyway ( no way I am now ) but that was my guys take on it mostly , makes things "brittle" over time (who needs that ?) hard on seals and the problems wouldn't show up until the warranty period was over ......again , I don't know if its true or not but im not chancing it.....maybe people that ARE using it can update on it after at least 3 to 5 years of use and see if there were any side effects ?

[clover]

Thanks Jacuzzi Jim and Chemgeek for the responses. I have found with a TA any greater than 30 my PH shoots up with any significant aeration in the tub. Unless I’m missing something, I don’t think I can have my TA any higher than 30. As for borates, yes, I am using 50 ppm from boric acid. As for my sanitizer, I’m using hydrogen peroxide. I know that’s not the normal way to sanitize but so far we really like it.

What is aeration to you?  Are you referring to effervescence, little bubbles popping off the surface of the water???