ph control, Am I adding acid to often

[wbrady]

30,000 gallon gunite
completed in October 2006, closed for winter in late November
Re-opened from winter in early April
Yes I do have SWCG, installed in mid April

I am adding on average 2 pints of muriatic acid a day. Is this normal? Will the ph stabilize? Should my plaster be cured by now? Should I be checking the chemistry everyday or just twice a week? PC says I only need to check it twice a week and maybe only once a week. Not sure how high the ph would go if I let it go for 5-7 days. Any input would be great. My wife thinks I should do what the PC says and check it just once a week.

Here are my numbers, done with basic kit the PC provided. I have ordered a Taylor k-2006, should have it today or tomorrow.

Date...... FC......... ph......... Acid added.......... Alkalinity
4/25...... 4.0........ 8.2........ 3 pints................ 130
4/27...... 4.0........ 8.0........ 3 pints................ --
5/1........ 3.5........ 8.0........ 3 pints............... --
5/2........ 4.0........ 7.8........ 1.5 pints............. 110
5/3........ 4.0........ 7.8........ none.................. --
5/4........ 1.5........ 7.8........ 2 pints................ --
5/5........ 2.5........ 7.8........ 2 pints................ 105
5/6........ 2.0........ 7.8........ 1.5 pints..............--
5/8........ 2.0........ 8.0........ 2 pints................ 110
5/9........ 2.5........ 8.0........ 3 pints................ --
5/10...... 2.5........ 7.8........ 2 pints................ 110

Thanks
Bill

[joelq]

Bill - I don't think what you're going through is that unusual at all. My IG with Pebble pool was finished in August 2006 and I've been having to add 1-2 pints of acid every couple days just to keep the pH under control.

You should start seeing the pH rise less quickly, however - from what I've read, it could take 6 months or even longer for the pH to stabilize.

One thing you might consider is adding some borax to your pool. Have you seen this thread http://www.poolforum.com/pf2/showthread.php?t=4712? Borax adds borates in your water and it acts as a pH buffer. I did that to my pool about a month ago, and now my pH is more stable and have to add acid only once a week.

[chem geek]

In addition to the use of Borates, you can look at this thread where lowering the TA level (using Ben's Lowering Your Alkalinity procedure) helps. It does seem that the Borates help more, at least in SWG pools, and let you turn down the SWG output. The other thing that helps in some SWG pools is to make sure the CYA level is at the manufacturer's recommendation which is often 70-80 ppm (which again lets the SWG get turned down more)

Richard

[wbrady]

I thought my TA was ok. anywhere between 80-130?
Should it be lower?
I would like to try the borax, sounds like it worked great for waterbear, I am a little scared to mess up the great looking water I have now. I sounds almost to good to be true, It would be great to here other success stories.

[chem geek]

When using a pH neutral source of chlorine (taking into account both chlorine addition and the using up or breakdown of chlorine), there is no need to have the TA higher than 80. The higher TA is only for when you use more acidic sources of chlorine such as Trichlor where a TA of 100-120 or so is more appropriate (or if you used other acidic chemicals such as non-chlorine shock on a regular basis -- this is not needed in outdoor pools).

So you can certainly lower your TA to 80. You could even go lower depending on your CYA level (with lower CYA levels you can go even lower in TA down to around 60-70). Since the TA is something very easy to increase again if for some reason you don't like or want to run at low TA, you can certainly try that to see if it helps. With the Borates, you pretty much commit to having them since only a drain/refill will remove them (though there's really not much reason to remove them).

Richard