New to me pool - questions

Jun 10, 2016
7
Ontario, Canada
Bought a house that has a pool so this is all new to me. Bought the recommend test kit. Initially had done a test at the local pool shop (Yes I know it can be off). I had a problem with the pool going cloudy initially. After the pool shop test they said the CYA was 100 which turned out to be correct based on the new kit. After reading the site I realized with a CYA of 100 the FC would have been too low. So I upped it. That stopped the cloudiness. The new test kit showed the FC to be 11.5 which is right in the range for the CYA of 100. My concern is that that the PH test can be off since it is above 10ppm. So my plan is to let the FC drop back towards 7 and test to make sure the PH is right. As for the CYA i know the only thing I can do there is remove water and add new. My plan is to keep the pool as is is for the summer. I will have to remove water in the fall to close anyways and I have swung back and forth on converting to a SWCG which would require higher CYA anyways. Just wondering if anyone had some thoughts on the plan. Just want to make sure I am doing everything right.
 
That is the quandary you face, reducing FC to test pH will put you at some risk and require additional effort. If the pool goes green it will be an expensive battle. You have obviously thought through your plan and it seems logical. I think it is a solid plan.

Although I am assuming a large pool...if it is small it may not be worth the hassle. Please update your signature with your pool details! Thanks and good choice to buy the kit. It's apparently not easy in Canada.

Last thing - you should do the dilution test for the CYA. For the pool water sample, add half pool water half tap water then add normal amount of CYA reagent and retest normally. Multiply your result by 2, this may or may not be close to 100 again. 100 is the endpoint of the CYA test and your CYA may actually be higher. Let us know.
 
Agreed. Everything you do hinges on the CYA right now. Definitely do the diluted test to confirm. It may actually be higher than you think. A partial drain would be the ideal scenario so that you can adequately manage FC and test pH as needed.
 
Okay the CYA dilution test ends up giving 50 so that means 100 right on in both tests.

Also a question about FC. I tested last night and got 11.5. Tonight doing the test again I am seeing 11. The pool was covered all day with a solar blanket and was only opened after dinner so the kids could swim. Can you lose that little FC over a daily basis if the pool is covered up and not really used?
 
Left the cover off the pool all day today. Kids used it quite a bit. FC test last night was 11.5. Tonight it is 8.5. Did the PH test and got 7.6 so that looks good. Did the TA test also and that was 120.

Plan is to keep it around 12ppm because of the CYA of 100 so by the pool calculator i should add 2.8 liters (94oz) of 10.8% bleach. Everything else looks good water is very clear.
 
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