Chlorine Gone in 2 days

[willkk]

Hello,

I'm 1 year into a new pool and am trying to adjust to using liquid chlorine rather than tablets because my CYA is near 100. I never needed to shock the pool before this point as the levels stayed pretty consistent. I added a full gallon of 12.5% chlorine to my 15000 gallon pool. I don't have a ton of experience but the last time I did that it brought my chlorine level to about 8 ppm. Unfortunately I incorrectly gauged the longevity of said chlorine and by day 6 I had algae growing on pool walls. I brushed this off and added 1 gallon of the same chlorine to the pool Sunday.... fast forward to Tuesday and I have 0 chlorine in the pool. How is this possible? Did the algae consume the chlorine? Does the CYA currently in the pool not adequately protect the liquid chlorine? I do not have a delta in the free chlorine/total chlorine. Should I just shock it again because I waited too long? Any help appreciated.... I never had these issues with the tablets and I'd rather wait until winter to drain the pool and dilute.

 

[Newdude]

Hey Wil and Welcome !!! You need a slight thinking adjustment to start your journey. The sun consumes 2-4 ppm *a day* across the land. Being later in the season with a lower sun angle (less UV) and shorter days, it’s lower demand right now, but being in TX you’ll still be consuming on the higher side of average. So if you add 8ppm that’s about 2 days worth. With swimmers or algae it could be less than 2 days.

You always want to treat to stay ahead of the demand, whatever it may be that week of th season.

Dipping below minimum you very well could now have algae too. Perform an Overnight Chlorine Loss Test to remove the sun from the equation. With no UV or swimmers overnight, any FC will still be there in the AM so you’ll know right away if algae was present to consume it.

If you fail the OCLT, you need to SLAM Process. Assuming the water is mostly clear as your post wasn’t all ‘HALP with my swamp’…. It should be an easier SLAM without a full blown infestation.

 

[BK MAC]

Also keep in mind that if your addition of 1 gallon of chlorine took you to 8ppm of FC you basically had no FC when you added it. Your minimum FC level should be 8, with a 11-13 target based on a CYA level of 100.

 

[an1vrsy]

Welcome to TFP! You have found the site that pool enthusiasts come to. No one here is trying to sell you anything. Trouble Free Pool methodologies does, however, require you to have a quality test kit. How do you test your pool water?

Fill out your signature so that the experts here can see what you have and make recommendations without having to constantly ask.

Go right ahead and continue to ask questions.

 

[PoolStored]

Also keep in mind that if your addition of 1 gallon of chlorine took you to 8ppm of FC you basically had no FC when you added it. Your minimum FC level should be 8, with a 11-13 target based on a CYA level of 100.

FC/CYA Levels