Thread: Amount of CL and CYA in each puck?

1. Amount of CL and CYA in each puck?

Does anyone know approximately how much chlorine and CYA is in each 3in puck? I'm trying to determine how much my current CYA level of 50 will raise after 3 months of using a puck each week for 12 weeks? Also if my current FC is 3, will 1 puck in a floater keep it a level of 3 over 1 weeks time with no swimmers and avg temp of 75 or will it drop to 2? I know that I will be adding liquid chlorine occassionaly to keep the FC in the 3-5 range, but just wondering what affect pucks alone will have over a month to month time frame? Thanks. It's a 20K Gal pool.

2. Re: Amount of CL and CYA in each puck?

You can use the bottom section of the pool calculator to see what effects each tab would have on your pool... you just need to know the oz of each puck - if their 7 oz or 8 oz and then you select the number of oz and trichlor and it will tell you there.

Pucks will also lower your PH/TA so just monitor those as well.

3. Re: Amount of CL and CYA in each puck?

For tri-chlor, which is what the pucks are, for every 1 ppm FC, there is 0.6 CYA put into the water as well. For di-chlor, 1 ppm FC =0.9 ppm CYA.

Someone please correct me if i'm wrong.

4. Re: Amount of CL and CYA in each puck?

In case you can't find it, there's a Pool School article on The Pool Calculator. Under "Effects of adding chemicals", select trichlor and put in your puck weight and also make sure to enter your pool water volume near the top of the page. The Trichlor pucks usually come as 6 oz, 7 oz or 8 oz pucks with the latter two the most common (the ones in my area are generally 8 oz.).

However, I note that the CYA number appears to be rounded to an integer (unlike the FC that has one digit after the decimal point). So as noted in the post above, just multiply the FC number by 0.6 to get how much CYA is added. That rule is independent of concentration of product or of pool size (i.e. For every 10 ppm FC added by Trichlor, it increases CYA by 6 ppm). Or you could enter in 10 times as much and then divide by 10 -- so put in 80 oz. for Trichlor in 10,000 gallons and you'll see 54.8 for FC and 33 ppm for CYA so that means for one 8 oz. puck it raises FC by 5.5 ppm and CYA by 3.3 ppm (again, in 10,000 gallons).

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