CYA added per 3" tablet of trichlor - the answer?

I talked to a tech support person at one of the big chemical companies and he said the following:

Trichlor tablets are about 54% CYA.

One pound of anything dissolved in 10,000 gallons of water will yield 12ppm.

Therefore, one pound of trichlor in 10,000 gallons adds about 6.5ppm CYA.

Each 3" puck weights 8 ounces, so if you use two a week that's adding 6.5ppm per week per 10,000 gallons.

Soooo...

If I have a 15,000 gallon pool and add two pucks per week, that's (10/15)*6.5 = 4.3ppm

Is that right?

TW

Edit

Close :D

Darn! Good catch. You are correct.

Color me stupid, guess I was thinking something else. :o

Carry on!

Cheers

What is the % of available chlorine stated on the bucket of tabs you have? Does it correlate with the CYA % so that together they equal 100%?

Just curious, cause if it does it would seem you could subtract the chlorine % from 100 and get the CYA total for other manufacturers pucks and sticks. EDIT- nevermind, I just checked, was thinking something else when I posted this. The label on my sticks says "90% available chlorine" and 99% trichlor...

I used to use 8 oz trichlor sticks from Blue Wave. I have 12 left. I had been contemplating adding them to my pool to get the CYA up. If I use the % you listed above, each stick would have 4.32 oz of CYA. Using the bleach calc, to raise CYA in my pool by 10 ppm (21,200 gal) I would need 27 oz or 6.25 sticks. Not very many, and I can easily see why I had so many CYA problems in the past and didn't even know it.

I've decided against adding more CYA, as I have about 10-20 right now, and my FC is holding good and staying lower on CL keeps me in line with the capabilities of my OTO test kit :)

Yep, I'm running 10-20ppm CYA as well, for the same reasons. But I like my auto-chlorinator and wanted to be able to calculate about when I needed to drain and dilute, rather than use the clunky turbidity test which doesn't go lower than 20ppm anyway. At this rate, it ain't long! :eek:

Hm. Ok, 8 oz * 54% = 4.32 oz of CYA. 4.32 oz of CYA in a 15k/gal pool = 2.25 ppm increase. Two pucks/week = 4.5 ppm increase/wk.

For the "standard" 10k/gal pool, one puck with similar chemical composition will give you a 3.4 ppm increase/wk. You can see how people burning through 4 pucks/week can really get high CYA levels.

Michael

Okay, I'm convinced. :rolleyes:

It's mostly bleach for me now too. I think I'll set my auto-chlorinator real low to trickle in some CYA and keep an eye on the numbers.

BTW, the Walmart Ultra-Bleach doesn't come with any analysis info on the label. Since it says "Ultra" is it safe to assume that it's 6%?

TW

I just bought 10 bottles of Wal-Mart Ultra. It says 6% on the label. It is just hard to find. I don't have one with me or I tell you exactly where it is located.

I'm looking at the label of the Walmart ultra bleach right now.

On the back side of the label right under where it says:

"DANGER: CORROSIVE:

It says:

"Contains sodium hypochlorite, 6.00% by weight"



Regards,

Mark

Doh!

There it is. :D

Thanks Mark.


TW