OFFICIAL water chemistry guidelines-what are they?

[kervis]

I suppose we all know that 7.2-7.8 is an acceptable range for pH, but then it gets inconsistent:

My spa log book says:
TA =         80-120
Calcium=  150-400

My owner's manual says:
TA=          adjust to 125
Calcium=  adjust to 150
pH=          7.4 to 7.6

When I bring my water in to the dealer to be tested, the printout says:

TA=          60-100ppm
Calcium=  200-400
pH+          7.2--7.6

The directions on my Calcium hardness increaser bottle say:
Calcium should be 100-200ppm

I am thinking that the difference in some of those numbers could have me using more/less of certain chemicals than may be really necessary.

Any thoughts/comments/answers on this?

Thanks!

[Nitro]

I wouldn't pay much attention to those ranges. Instead I would learn how the variables relate to each other, and how to keep your water balanced. The main problem in spas is rising pH due to aeration (air injection). The trick is to lower your TA enough to stop it, or at least reduce it greatly.

You can go here and learn about Water Balance. It will explain it in detail.

Let us know if you have any questions.

[Vinny]

There is one place that I get my info from and that's the Taylor booklet that comes in the K-2005 kit (I'm sure it comes in other kits as well). I DO NOT trust dealer info as some dealers either may not know how to use their computerized testing machine or just want to sell you stuff. Remember any "computer" that gets calibrated can be calibrated wrong!

I have not had any problems following the Taylor book and have found a local pool dealer to not know what they were saying about certain water parameters.

It looks like your log book is following the Taylor book.

Then again if you have questions - you can ask here.

Hope this helps.

[Nitro]

I agree with Vinny, the Taylor booklet has taught me a lot.

However, it may be difficult to keep your parameters in certain ranges if you don't understand the basics of Water Balance. For instance, don't expect your pH to stay bwrween 7.4-7.6 if your TA is 125 ppm. It just isn't going to happen in a hot tub with plenty of air jets. This is where beginners have problems (too high TA), and you're not going to find that info in the Taylor book.

I'll refer you again to my post Here where I explain Water Balance. The key point is that your pH wants to rise in a hot tub with air jets. The best way to keep it from doing that is to lower your TA (60-80 ppm).

Also, there's a website called The Pool Calculator, that will let you plug in values and see where your overall (Satuation Index) balance is. It's an expanded version of the one that comes with the Taylor kit. It will also let you see how the different variables (CH, TA, pH) relate to each other to provide balanced water.

[Vinny]

Nitro,

From what I learned the higher the TA (within reason) the more it locks in the PH which is why you need to use a lot of acid in order to lower PH with high alkalinity. A TA of 60 could produce PH swings where at 120 may not. I've never had to do this but I imagine that lowering your PH and alkalinity with acid and then bringing both in line will lock them in together.

I have said this many times - everybody's water reacts differently and in my water I have noticed my PH drifts down vs up. It also corresponds to the alkalinity reading and how quickly it dives ... the higher the alkalinity the slower it moves down. As a matter of fact I have found that using dichlor makes the PH slide down quicker than using bleach since apparently the end result of chlorine being used is an acidic reaction. I can go many weeks without my PH moving using bleach vs 3 weeks with dichlor.

Now to complicate matters with this I only use baking soda in my spa to raise both PH and alkalinity ... this doesn't work in my pool. There I raise the PH with Borax and then raise the alkalinity with baking soda and again it gets locked in for a while.

You are the first person I've heard to say lower alkalinity to combat PH going high - usually it is said to get the PH in line and lock it with the alkalinity. If PH creaps up usually the thing to do is get the PH to 7.2 and lock it in with the alkalinity, watch it, when it gets high hit the water with acid to get them down and start the process all over again.

[tony]

I also find that keeping a lower TA prevents my pH from rising.  My TA out of the tap is at about 80.  My pH stays most stable if I keep TA at that level.  Higher TA will pull my pH up.

[Nitro]

Vinny,

You are correct that having a higher TA will prevent pH swings. However, it will only prevent swings from outside sources. i.e. the addition of Acid or Base. However, having a higher TA will cause the pH to rise more from aeration, i.e. the injection of air. In order to counter this pH creep, some kind of acid must be used i.e. Acid, Dichlor, or MPS. By lowering TA you will get larger swings from the addition of acid or base, but you you'll have less pH rise from aeration. However, if you don't add acid/base, or very little, it's a non-issue. Another way to reduce pH rise from aeration, is to add Borates (Borax) to the tub.

I agree that everybody's water acts different. However, I believe it depends on what is in the fill water to some degree, but what's put into the tub to a much larger degree. Not knowing everything you've put in your tub it's difficult to tell. But the main reason pH is lowered is the addition of something acidic, which could be Dichlor, MPS etc. However, using Bleach is relatively neutral, i.e. high pH while adding, acidic reaction when used up. So if only bleach is used the pH will have a tendancy to rise from aeration. Lowering TA and the use of a pH buffer (Borates) will reduce, if not stop it.

My tub has 60 ppm TA, 50 ppm Borates and my pH has stayed rock solid at 7.8 for the last month, since my last refill. After a refill, I add acid to lower my TA from 100 to 60 ppm, calcium to raise my CH from 100 to 200 ppm, Borates to raise it to 50 ppm and Dichlor to raise my CYA to 30 ppm. After that the only thing I add to my tub on a regular basis is bleach. Sometimes, I'll use MPS if I have high bather loads, but not on this fill. I rarely add acid, unless I'm lowering TA to fine tune it. And I never use Baking Soda, unless I mess up and add too much acid (only happened once).

Just out of curiousity, what level do you keep your TA at?

[Vinny]

Actually I haven't measured TA for months (year?) only because I originally measured my PH and alkalinity out of the tap and both were low (PH - 6.8, alk below 80). They rise proportionatly together using baking soda and whenever I get to a good PH my TA is "within range".  I have in the past used Borax in a pinch to rase the PH but found it didn't stay because my alkalinity was too low where as when I use baking soda it stays for weeks. I know Borax for raising PH ... Are you saying it adds different properties to the water vs soda ash?

In the past I have "balanced" my water within the Taylor specs but recently I have not been adding calcium. My tap water is also low in calcium and I used to bring it up to 150 to 200 PPM.

In the 3 1/2 years of owning my tub I have not had PH creep up but come down ... same as in my pool and I used bleach this summer except for a brief period where we went on vacation where I used trichlor.

I can measure it and tell you what it is. Unfortunately I can't do it for a couple of days as I negleted the tub and had to pour in a whole lot of bleach to kill the nasties. I'll let you know what it is in a few days.

[Nitro]

Well, if you haven't been measuring TA, it's hard to tell where it is. I'd say if you have a problem with pH decreasing, your TA is on the low side, i.e. much less than 80. My point above was that if TA is on the high side, i.e. greater than 100, pH has a tendancy to rise via aeration. I'd be curious to know where yours is though. If you can measure and post it whenever get a chance that would be great.

Borates act as a pH buffer. i.e. they slow down the rate pH increases via aeration. Not to mention they give the water a nice silky feel to it. You add them by adding Borax to the tub. You also have to add acid to counter balance. Here is an excellent writeup about it.

[Vinny]

OK, I was able to test my alkalinity

PH was 7.2 before adding all that bleach and its now at 7.4 and my alkalinity is at 80 PPM. I was planning on adding some baking soda to bring up the PH and alkalinity and give you a reading with that but since the PH is OK now I'm leaving it alone for now. As far as I remember bleach does nothing to raise the alkalinity

About the comment of "Well, if you haven't been measuring TA, it's hard to tell where it is." I have to disagree. Once you tested water parameters for a while and get a feel for what your water is doing then you don't need to test certain parameters too often. I found with my water that my PH and alkalinity rise and fall together and that when one is in an acceptable range, in this case I measure PH, then the other should be OK. I will say that at a PH of 7.8 my water's alkalinity is a bit on the high side and when I use dichlor exclusively alkalinity will fall and bring the PH down. But a lot of people either haven't tested their water enough or their water acts differently than mine. I believe that everyone should understand balancing their water but I think a lot skip this understanding.

Now about borates or borax - I didn't read the whole writeup but have been around the originator - pool solutions - for about 8 years. I guess the idea in the writeup is to use a lot of borax and "saturate" the water. The original concept was to use borax as a grocery store PH up and I do use it in my pool. As I said using baking soda in my spa brings up the PH as well where it has no effect to PH in my pool. I have read the using high levels of borates in the pool can act as an algecide along with proper water care procedures. I haven't had the need for algesides in my pool ... although last year I did have a problem with some type of alge eating my cya but that was taken care of by using large quantities of bleach for many days!

[Nitro]

Vinny,

80 ppm TA is a lot lower than 120 ppm, which is technicaly still "in range". I can guarantee you if you raise your TA to 120, your pH will keep rising from aeration. In my earlier post I said, "The best way to keep it (TA) from doing that (creep) is to lower your TA (60-80 ppm).". My point was (and is), "Don't expect your pH to stay between 7.4-7.6 if your TA is 125 ppm.". And you will not find that information in the Taylor books.

When I said, "Well, if you haven't been measuring TA, it's hard to tell where it is.", I meant it's hard for ME to tell where YOURS is. I guess it was hard for you to tell too, because you had to measure it to know. FYI, I rarely need to check my TA, because I know where it's at (60 ppm). The only thing I check regularly is FC, and sometimes pH.

I was under the impression your TA was higher (~120), because you seemed to disagree with my above post. Also, you said, "From what I learned the higher the TA (within reason) the more it locks in the PH which is why you need to use a lot of acid in order to lower PH with high alkalinity." That is true, but doesn't account for aeration. A TA above 100 will make it very difficult to keep pH < 8.0 in a hot tub with jets/air.

If you want to prove this fact for yourself, try this. Add Baking Soda to your tub to raise TA to 120, (about 3 oz). Measure your pH. Then kick the jets and air on for 30-60 mins. Then measure your pH again. Your pH will be much higher then before you turned on the jets. This is because aeration raises pH more with a higher TA. But I wouldn't recommend doing this until right before your next drain. Otherwise, you'll have to add acid to bring your TA/pH back down.

Lastly, Baking Soda has little effect on pH directly. Baking Soda raises TA, not pH. However, because your TA is higher, that causes your pH to rise from aeration. The reason why your pH doesn't rise in your pool from the addition of Baking Soda, is because your pool has a lot less aeration than your hot tub. Therefore, a higher TA in a pool won't effect pH as much as it does in a hot tub.

[Mr._Bubbles]

Like Vinny, my PH keeps getting lower as time goes on.  After a fresh fill, I have a hard time keeping the PH down.  After the water starts to get "old" I have a hard time keeping the pH up.

[stuart]

Like Vinny, my PH keeps getting lower as time goes on.  After a fresh fill, I have a hard time keeping the PH down.  After the water starts to get "old" I have a hard time keeping the pH up.

I have a similar problem but nothing to do with my PH...

[Mr._Bubbles]

 

[Nitro]

Like Vinny, my PH keeps getting lower as time goes on.  After a fresh fill, I have a hard time keeping the PH down.  After the water starts to get "old" I have a hard time keeping the pH up.

If you have a problem keeping pH up, you may want to raise your TA with Baking Soda. Where is your TA at now?

Also, Dichlor is acidic and will lower TA/pH over time. If you don't raise your TA periodicly, it will get too low.