how much CYA will a 50lbs of tri clor add?

[sunofthebeach]

It is cheaper and easier for me to use chlorine pucks in the in line feeder. Last year I used the Cal Hypo pucks, this year I am using the CYA based chlorine pucks. I bought a 50 pound bucket that should last me the entire season.

How do I tell how much CYA the pucks will add if I use all 50 pounds?

P.S. I open my pool to 0 CYA every year, so I am not worried about the fact that I am adding CYA to my pool.

[mbar]

Here is a post my chem geek:

Re: Measured Density of Dry Chemicals
The CYA pucks vary in size and the ones I am using are 3" and 8 ounces weight. There are also 7 ounce and 6 ounce versions that are also 3" in diamter. There are 3 ounce 1" and 1 onuce 1/2" pucks (or tablets) as well.

Anyway, one 3" 8 ounce puck will add 5.5 ppm FC and 3.3 ppm CYA in 10,000 gallons. An even faster way to add CYA and chlorine at the same time that dissolves faster and has more CYA in it is to use Dichlor powder where 1 pound (16 ounces) will add 6.6 ppm FC and 6.0 ppm CYA in 10,000 gallons. To add CYA by itself quickly, there is the Natural Chemistry product called Instant Pool Water Conditioner found at this link. And of course you can add regular CYA though that is very slow to dissolve (putting it in sock/hose over a return makes it dissolve faster).


I'll let you do the math

[sunofthebeach]

alright so 2 8oz pucks is a pound and it will add about 3ppm of CYA to my 24,000 gal pool.

so

50 pounds of pucks will add 150 ppm to my 23,000 pool?

[mbar]

I think that is based on 10,000 gal., so it would add 75?

[chem geek]

sonofthebeach is correct. Two 8 ounce pucks is one pound and one puck in 10,000 gallons increases CYA by 3.3 ppm. So in 23,000 gallons,

(2 pucks/pound) * (50 pounds) * (3.3 ppm/puck-in-10,000-gallons) * (10,000 gallons / 23,000 gallons) = 144 ppm CYA.

or 50 pounds of pucks is 100 pucks and this would add 330 ppm in 10,000 gallons so in a larger pool it's less so 330 * (10,000/23,000) = 144

This assumes no dilution from splash-out or rain overflow or backwashing.

Richard

[mbar]

I seem to stink at math too Richard Oh well, at least I can cook

[Jakebear]

Richard, indulge me please.

So let's check DH calculations. Using 7 oz pucks in 27038 gallon pool. He figured 15 pucks.

Using your formula, I get 2.789724515 ppm/lb in 27038 gal pool and therefore need 3.5845833333333 pounds of pucks to get a 10ppm increase.

Which means 8.19 pucks.

Don't want to put you in the middle but......................

[chem geek]

The formula is about 3.3 ppm CYA for 8 ounces in 10,000 gallons. So,

3.3 * (7/8) * (10000 / 27038) = 1.07 ppm CYA per 7-ounce puck in 27,038 gallons. The accurate calculation gives 1.08 ppm CYA (the 3.3 was rounded).

I'm not sure what you were looking for.

Richard

[Jakebear]

At 1.07 ppm CYA/7 oz puck it should take ~ 9.3 pucks to raise it 10 ppm. We have put 12 pucks in and have not seen the CYA budge. Tests this AM were:

pH 7.4
FC 3.6
CC 0
TA 90
CYA <30 ppm
Temp 83
All with Taylor 2006 kit

Maybe the CYA was lower than we thought (22) to begin with. I just want to "quit with the pucks already" --- they make a black scum ring around the pool and I didn't have that when the CL Pump was in use.

I sure wish there was a different test for CYA -- I just got off the phone with them --- NOPE --- unless you go electronic colorimeter (Taylor doesn't have) and it is still turbidimetric.

[chem geek]

Though Trichlor is cheaper, a faster and more efficient option for adding CYA is Dichlor. At least it dissolves right away. Anyway, I found that using Trichlor in my own pool took a little more than I expected to get the CYA to rise, but the turbidimetric test is clearly not precise visually and is probably quite prone to error at the lower CYA levels where other turbidity of the water itself would become even more important.

CYA presumably adheres to pipes and pool surfaces, at least somewhat, so some that gets added probably doesn't get measured in the water test.

Richard