Water test results of almost new pool

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V

vtdhc

0
Aug 1, 2014
24
Saint Albans, Vermont
We have a newly installed IG pool and I just got the test results from the first water sample. I was a little surprised to see the results are not really ideal since the water seems sparkling clear from my perspective. My test kit is the TF-100 and these are the results....

FC - Free Chlorine = 15 ppm
CC - Combined Chlorine = 2.5 ppm
pH = 7.0 estimated between 6.8 & 7.2 on chart from basic kit
TA - Total Alkalinity = 70
CH - Calcium Hardness = 375 ppm
CYA - Cyanuric Acid (stabilizer) = 20

So the chlorine is way high and the CYA and PH are low. I intend to add some borax for the PH.

First a little history on how we got here. Initially we were steered towards a chlorine alternative product called "Advanced Blue" from the pool store and we did add about 3 cups of this to the pool and also some shock. Shortly after I decided this was going to be an expensive solution and decided to change to chlorine. We have been using stabilized chlorine 3" pucks in a chlorine feeder. The feeder was set at a setting of three, then we had the water tested by the pool store and they said to increase the chlorine feed to five. I have now set the feed rate down to two since the FC tested at 15 ppm.

Also from reading on this forum I now understand that Trichlor pucks are going to create a CYA problem at some point if I continue to use them so I will likely switch to liquid chlorine down the road. I just bought a 50 lb supply of these pucks so I think I will use them for a while. Since my CYA test was at 20 I have a ways to go before that reading is a problem. What I'm not sure of is how quickly the CYA is going to climb while using the Trichlor pucks. Does anyone have any advice for me ?

Thanks,
Dave.
 
One thing I forget to mention was the CC test of 2.5 ppm. The advice on the forum for a CC reading above 0.5 is to SLAM the pool, but the pool doesn't appear to need a SLAM. The water is as clear and odor free as drinking water. Looking at it or swimming in it you wouldn't think it needed anything. Could it be that the pool has Potassium monopersulfate in it from the shock from the pool store? This is a quote from the forum concerning Potassium monopersulfate. "Potassium monopersulfate (a common non-chlorine shock) will show up on FAS-DPD chlorine tests as CC. There is a special reagent you can get to neutralize the potassium monopersulfate so you can get a true CC reading."

Dave.
 
What are the ingredients listed in the "shock"? If it's a non-chlorine shock, it may be causing a false CC reading.

If you know how many pucks you put in, you can use PoolMath (http://www.troublefreepool.com/calc.html) to calculate how much CYA you've added. Put your pool size in number of gallons at the top, and then scroll down to the bottom section where it says "Effects of adding chemicals". If you don't know the weight, assume each 3" puck is 8 ounces (some weigh a little less). CYA can take up to a week to show on a test, so you'll want to calculate how much you want to add, wait a week after it dissolves, and then test and adjust.

If you haven't added much CYA, yet, it will be faster to buy CYA and switch to liquid chlorine now. Pucks will last a long time when kept dry, and you can use them as a stopgap for those periods where you won't be able to add chlorine every day (vacation, for example).
 
Using pucks, it is dissolved by the time it hits the pool so it should show up on the cya test within an hour. The pucks themselves are slower to completely dissolve which would then show the complete effect of an individual pucks cya addition.
 
I did some research on what was added to the pool from start up. Initially the pool had been filled with drinking water from the local town water utility and had a greenish tint from chemicals added for water purification. I forget what it was called but the pool installer said the tint would be gone in a few days. On July 11 we added 1 qt of metal magic and 64 0z of Advanced prep. (to remove metals & minerals from the water). The next night we added 3 gallons of Sur-shock (12.5% sodium hypochlorite, and 87.5% other). Two nights later we added 36 oz Advanced blue (19.8% copper sulfate pentahydrate, 80% other).

Also from start up we had the chlorine feeder filled with trichlor chlorine pucks and the feed rate set to 3. After adding the above and getting the first water test from the pool store they had us turn up the chlorine feeder rate to 5 and had us add a half bucket of Alkalinity up (baking soda) and another 8 oz of Advanced blue.

After this start up I had started to read info from this website and had decided to change to chlorine only and ordered my test kit. So I guess I'm confused with my initial test results posted above. Looking at the pool water and swimming in it the water seems perfect. Absolutely crystal clear and no other problems that I can detect or anyone else who has used the pool. If I understand my test results I have a problem with CC at 2.5 and should be shocking the pool. But with a CYA of 20 and FC = 15 I think I already am shocking the pool but not really meaning to. Do I need to be concerned with the CC test at 2.5 and the FC test at 15 ppm? Any ideas how it got like this from what I listed above. I really expected my test results to be nearly ideal but it appears they are not. What should my next steps be?

Thanks,
Dave.
 
I trust your results more than the pool store's. Even if their test is accurate, the chlorine test is time-sensitive; 15 minutes is too long to wait before testing it to get a reliable reading.

Re-test and see if CC is still running above 0.5. If it is, the chlorine is interacting with something to form CCs. The question is, what's in the water for it to interact with? The most likely answer is that there is something organic in the water, like algae. If it's algae, it's in the early stages where you can't see it, yet. Also, you have something of a moving target since those pucks are going to continue to increase the CYA. This is fine for now since your CYA needs to go up, but your shock level will change, too.

The Sur-Shock is a high concentrate liquid bleach, so that's handy to have. What is Advanced-Prep (chemically what is it)?
 
Just one thing to add about your CC test. As soon as your done with the FC test, when it turns clear move right to the CC test. Have your CC test reagent ready and add 5 drops. If you wait too long the sample starts to turn back to pink. ?
 

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I'm not sure what advanced prep is chemically. I don't have any more and the webpage only says it removes minerals such as calcium, iron and lime. I could go to the pool store and get that off the label if it is needed. I plan to do another test sometime tomorrow. I'm really hoping this is just a matter of tweeking the way I did the test, like waited too long before taking the next step.

Thanks.
 
I did another water test and the result was great. It seems my procedure was the problem. As suggested by pwrstrk (Jeff) I was waiting too long after doing the FC test before starting the CC test. This time I was ready and started the CC test immediately and got this for a result....

FC - Free Chlorine = 8 ppm
CC - Combined Chlorine = 0 ppm
pH = 7.5 after I had added 76 oz box of borax
TA - Total Alkalinity = 80
CH - Calcium Hardness = didn't test this, last time was 375
CYA - Cyanuric Acid (stabilizer) = still at 20

So as I was hoping it was just a matter of changing the way I did the test. I would have thought this would be made clear in the instructions but It was great to have the forum experts set me straight. Thanks all for the good advise.
 
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