Lowering PH - Use PH Down, Muriatic Acid or Vinegar?

[Quickbeam]

Thanks Dunecritter,

This is all new to me, so I just want to make sure I don't screw it up too badly! I'm just waiting for the electrician to come by and install the breaker, and then I'm good to go.

[Vinny]

Sanitizer may affect your readings if it's too high. I know your not using chlorine but too high chlorine will possibly bleach out the other readings. My advice would be check the readings before you add any large amounts of sanitizer. I am not personally familiar with sanitizing with peroxide so I can't say how it will affect readings.

Adding "stuff" to the water will affect the PH. Most people add PH up if they need to raise their PH but I add baking soda. For some reason my tub's PH and not my pool reacts to the baking soda to raise PH. It was explained to m that it has to do with the tub's aeration and I could buy that IF it didn't raise it and keep it there right off the bat. It still may be the reason but I haven't been convinced. Typically baking soda is for raising alkalinity.

The PH of hydrogen peroxide is between 1-5 depending on the concentration so it will consistently try to bring your PH down. I personally would start with a PH of 7.6 to 7.8 (within range but 7.8 is slightly high) and see how the PH goes once you start to add the peroxide. Alkalinity plays a role in locking in the PH so if you are on the high side of the range the PH will not drop quickly.

So you get your water's chemistry "correct" and then you add peroxide. If all is good you shouldn't notice any drop in PH, you go into your new tub and have to add peroxide every night you go in (not sure if this is the scenario - it is with chlorine) and possibly after a couple of days the PH is starting to drop. Or you've been adding peroxide every day for 2 weeks and the PH is now starting to drop. You now know approximately how long it takes before the PH starts to lower.

I don't know if Taylor makes a liquid peroxide test kit but if they do - go with it. I am partial to the liquid kits myself and once you get into the swing of things - it is very easy. I test pool and tub water over here and both take about 10 minutes total to do.

[Topline Mike]

I prefer a more accurate test kit.  I read about test strips vs. a test kit on another forum, and that's where I got my information. 

Well there you have it....Read it on a public forum....Gotta be legit if its on the internet! LOL

If you read chem geek's first sentence, you would understand.

[Topline Mike]

Quickbeam, just make sure you give the tub some time after adding chemicals like PH Down to fully take effect...Best to take a reading 12-24 hours after adding the Dry Acid to bring down the PH.

Nope, can't agree with this one.  You are dealing with a 400 gallon pool with jets that will blow you out of your seat.  If you add a chemical and turn the pumps on high for 20 minutes, don't you think it will be mixed well enough?  Think of your spa as a giant blender, it mixes well.  Now if you're talking about a 30,000 gallon pool, I can understand the wait.  Someone tell me my logic is wrong, and I'll go away.

[Dr. Spa™ Ret.]

Thanks everyone for your replies.

I know from experience that this same water in our house leaves calcium deposits. I can see it in tea kettles, etc.

I would suggest not boiling water in your spa

[Quickbeam]

Yeah, I had kind of figured I wouldn't boil the spa water, at least at first. And even then I'll only boil it when there is someone in the spa I don't particularly care for.

I'm also pretty sure the deposits in the kettle aren't there because the water has been boiled. Much more likely it's because it's hard water.

[Quickbeam]

Sanitizer may affect your readings if it's too high. I know your not using chlorine but too high chlorine will possibly bleach out the other readings. My advice would be check the readings before you add any large amounts of sanitizer. I am not personally familiar with sanitizing with peroxide so I can't say how it will affect readings.

Adding "stuff" to the water will affect the PH. Most people add PH up if they need to raise their PH but I add baking soda. For some reason my tub's PH and not my pool reacts to the baking soda to raise PH. It was explained to m that it has to do with the tub's aeration and I could buy that IF it didn't raise it and keep it there right off the bat. It still may be the reason but I haven't been convinced. Typically baking soda is for raising alkalinity.

The PH of hydrogen peroxide is between 1-5 depending on the concentration so it will consistently try to bring your PH down. I personally would start with a PH of 7.6 to 7.8 (within range but 7.8 is slightly high) and see how the PH goes once you start to add the peroxide. Alkalinity plays a role in locking in the PH so if you are on the high side of the range the PH will not drop quickly.

So you get your water's chemistry "correct" and then you add peroxide. If all is good you shouldn't notice any drop in PH, you go into your new tub and have to add peroxide every night you go in (not sure if this is the scenario - it is with chlorine) and possibly after a couple of days the PH is starting to drop. Or you've been adding peroxide every day for 2 weeks and the PH is now starting to drop. You now know approximately how long it takes before the PH starts to lower.

I don't know if Taylor makes a liquid peroxide test kit but if they do - go with it. I am partial to the liquid kits myself and once you get into the swing of things - it is very easy. I test pool and tub water over here and both take about 10 minutes total to do.

Thanks Vinny,

Right now my tap water PH is 7.4 which I think is pretty good. Actually all the numbers for my tap water are pretty good, except for the TA, which is high. I read somewhere that when the PH is in range, but the TA is high, once the aeration starts on the tub, the PH will go up. Because my readings are O.K. to start with, other than TA, I thought I'd add the hydrogen peroxide first, turn on the jets, etc. and see what happens and if the PH has in fact increased then I'll work to bring it down. At least that what's I'm thinking.

Now I just need to get the electrician back to put in the breaker so I can get started and get soaking!

[Tman122]

I agree that your not to far off and I would relax, enjoy your tub and be sure to sanitize after use. Play with your balance slowly.

[dunecritter]

[/quote]

Nope, can't agree with this one.  You are dealing with a 400 gallon pool with jets that will blow you out of your seat.  If you add a chemical and turn the pumps on high for 20 minutes, don't you think it will be mixed well enough?  Think of your spa as a giant blender, it mixes well.  Now if you're talking about a 30,000 gallon pool, I can understand the wait.  Someone tell me my logic is wrong, and I'll go away.
[/quote]

Its not really an issue of getting the Dry Acid time to mix with the small amount of water as I completely agree with the jets on its literally "Mixed" evenly with the tubs water in a few minutes.  But rather allowing the Acid enough time to fully dissolve from its crystal form and take its adverse affect on balancing the PH level. The PH level continues to change for up to a few hours or even longer in some cases and this is why one should wait and give the Acid more time to react and change the water balance before prematurely reading the PH levels.
 This might not be the right example but I'll try to make an example of it...If you want to acid stain concrete you would apply the acid to the concrete surface and wait from say 10 minutes to 4 hours to achieve the desired color or intensity of color that one desires and then you would apply a solution to get the acid to stop reacting with the Lime in the concrete. So the acid continues to react and change the color for many hours until it reaches a point that it has stopped reacting or you physically apply a solution to neutralize the acid.
Or maybe like taking a pint of automotive enamel paint and adding a catalyst to it giving you "X" amount of time to use before the paint hardens. This is called "Pot Life" The paint is thoroughly mixed well instantly by manually stirring  and is in a liquid form for roughly 2-4 hours depending on the product and then once the pot life has expired it turns into a jelly form and then soon after a solid state. So even though the catalyst was mixed well at first the chemicals mixed continued to react changing the state of the paint for 2-4 hours until it was no longer a liquid form.
These might not be very good examples but its all I could think of.
 I have always been told to give much time after adding Dry Acid to take proper readings. Not so much on sanitizer levels as its pretty much instant even though it will continue fight bacteria for "X" amount of time as we are not measuring the level of bacteria but the level of sanitizer can be measured within minutes after adding with the jets on to mix thoroughly.

[chem geek]

I know that the Muriatic Acid just needs circulation, but I didn't think dry acid (sodium bisulfate) was slow to dissolve -- I haven't used it myself so can't comment from experience.  I'd bet that it's pH effect is pretty much as fast as Muriatic Acid from a practical point of view in terms of, say, 5-10 minutes of spa jet mixing.  Of course, running spa jets aerates the water so will tend to have the pH rise back up.  That's the process of how one can lower the TA -- by adding acid and aerating, adding more acid, etc.

Due to the small spa water volume, even running the circulation pump mixes the water pretty well.  Probably running the spa jets briefly (say for one minute) might minimize the carbon dioxide outgassing while being enough for some decent circulation.

[Quickbeam]

Well, we went for our first soak last night, in our first ever hot tub! This has been quite a journey for us. As many of you know, we were restricted in both the size and weight of tub we could go with as we put our tub on a roof deck. We ended up with the Jacuzzi J-345. It suits both our size and weight restrictions and we really enjoyed our first soak. Time will tell, but hopefully the tub stands up.

I’ve been fighting the water balancing a bit, but right now my numbers are as follows:

PH - 7.4
TA - 100
CH - 130

I ended up using the PH down instead of the muriatic acid. I couldn’t find the 16% muriatic acid, and the potential of the odor with the 32% concerned me, as odors do bother my wife with her chemical sensitivities. On a positive note, after our soak last night she didn’t show any negative effects, although I have added quite a bit more PH down since then. We’ll go in again tonight so we’ll see how she does with that.

And after our soak tonight, if the aeration (jets) doesn’t shoot the PH up again, I think I’ll leave everything where it is. I’m just slightly above -0.2 on the saturation index on the “wheel” with the Taylor test kits, so while it is close to the edge, it’s still within the parameters they have.

If anyone has any opinions / ideas I’d love to hear them.

Otherwise, I just want to give a big shout out to everyone on this website. Your help has been invaluable to us. Just can’t thank all of you enough for all your help and input.