Where to start?

[sevilledp]

Hello. Long story short I've decided that my pool "professional" didn't do as much as he should after creeping around on this website and realizing that 10-20 minutes a week probably wasn't enough time to keep the pool in tiptop shape. I purchased the tf-100 test kit and the numbers are as follows.

ph-8.2
fc-2.5
Cc-.5
ch- 700
Ta- 110
cya- 50
Salt- 3300

So the pool is almost exactly 1 year old and the only problems I've been having are scaling problems. It's known that we have really hard water out here so I just kind of accepted it as something I would have to deal with. However, I decided to test the CH of the fill source (city water) and was surprised to find that it tested at 200. So surprised that I repeated the test 2 more times and got 200 each time. I consulted pool math and understand what I need to do to adjust the rest of the other results to optimal. My question is 2 fold.

1) Is there a way to lower my CH without replacing 80% (according to poolmath) of my pool water?
2) If not, should I wait until it is done refilling and then test again to determine proper course of action?

Thanks in advance.

 

[chiefwej]

High CH can be managed. Where I am in Tucson the water is harder than yours and I have successfully managed CH levels over 1,000 for a year without any trace of scale, before draining and refill to get it down again.

When you add muratic acid to lower the pH you will see that your TA will also come down a bit. As to the CH being a bit high, there isn't much you can do about that, since the only way to lower is to replace high CH water with lower CH water. If You put all your test results, (along with the pool information like capacity, plaster for surface info, etc.) into Pool Math, you will see a number near the bottom of the chart listed as CSI. THAT NUMBER IS IMPORTANT. It is calculated from several factors you have entered including CH, TA, pH, temp, etc. The CH tells you how much Calcium Hardness is in the water. The CSI (Calsite Saturation Index) tells you if that calcium will stay in the water or perciptate out as scale on the surface of the pool if the CSI gets too high (above +0.6). If the CSI is too low (below -0.6) it can actually damage the surface of the pool by dissolving the calcium in the plaster and grout. Although there are several factors in the CSI the only one you control directly is pH. So you have to carefully manage the pH.

If you have any scale or if your CH is currently on the high side of "normal" you should try to keep the CSI just SLIGHTLY negative. By slightly I mean well within the safe range. I generaly shoot for a number between -0.06 and -0.2. This will prevent additional scale from forming without getting close to the corrosive effects that can be caused by getting too far(0.6) on the negative side. As the CH continues to rise this becomes more and more of a balancing act, until you have to drain and refill to lower the CH.

If you are running a SWG, and it appears you are from the salt level, constantly rising pH will make that balancing act even more difficult. Adding borates can help a bit with stabilizing and controlling pH rise, but you need to study that before considering it.

Probably, way too much information to digest in one post, but sometings for you to begin to consider.

 

[chiefwej]

Also to allow us to help you without asking the same questions over and over again, please put all the information about your pool into your signature line. You can see mine or others for details. Spend some time studying Pool School articles and it will all start to fit together for you.

Welcome to TFP.

 

[sevilledp]

Thank you so much. Poolmath has my CSI as .79 and that my target should be -.55.
Also, I noted the "breeze 320 swg" in my sig line. Is it not visible, or is there a way that I can clarify it more?

 

[Agent99]

I get 0.89 for your CSI but regardless, adding acid only to move your pH from 8.2 (it could be higher...I think the pH maxes out at 8.2) down to 7.5 puts you at 0.21.

As chiefwej said, the acid will also knock your TA down and that will serve to drop your CSI a tad further so no big deal. (Assuming 10, your CSI is then 0.16).

Once you lower the pH, measure it daily and note how long it takes to rise to say, 8.0. TA tends to keep the pH from moving too quickly so you'll need to judge as you measure your pH how much to lower your TA to keep the pH relatively steady.

Also of note, it is suggested for SWG to have a CYA of 60 to 70. Increasing your CYA will also knock your CSI down just a tad. (Including the 10 from TA, CYA at 60 puts you at 0.14 for CSI).

 

[chiefwej]

I don't know where you got a target CSI of -.55. If you read the notice on Pool Math the recommended range is from +0.6 to -0.6. The actual target for CSI is zero, but within that range is considered acceptable. Anytime you let the CSI get above +.6 (as it is now) you are adding scale to the pool.