chlorine calculations and questions

Hi,

I was at BJs last weekend and they had:
- hth shock - $2.20/lb, 60% calcium hypochlorite
- hth granules - $1.25/lb, 56% calcium hypochlorite

Here are my questions:
- both would be fine for shocking my pool?
- both contribute additional chemicals that are unwanted (ie. cya)?
- What is the calculation for how much to add? (10ppm=x lbs.)?
- What is the bleach calculation? (I know there is a calculator, but it would be handy to have the calculation)

I know thats a lot of questions but if anyone has the answers handy, it would be appreciated.

tia,
jd

In the info Ben has on the other site, he says HTH shock and not shock are essentially the same thing, calcium hypochlorite. As you can see the shock is 4% stronger, and almost twice the price. Can you say scam?

Both would be fine for shocking your pool as far as doing the job of a shock goes. After that, it depends on the type of pool you have. I have an IG with vinyl liner and a de filter. When I used calcium hypochlorite in the past, it made my water hazy until it filtered out. Then it locked up my DE and I had to break down and do a manual clean.

To my knowlege calcium hypo is not stabilized, ie it doesn't have CYA added. Just the calcium which may or may not be beneficial depending on the type of pool you have.

I'm not sure which strength this is for, but I was looking for something else this morning and saw this- 100 grams of cal hypo will raise chlorine in 15,000 gallons of water by 1 ppm.

I don't know what you mean by bleach calculation. Ben has said elsewhere that 3/4# of cal hypo is equivilant to 1 gal of 6% bleach, if that's what you mean.

1 lbs of pure chlorine is about 1 gallon of 12.5% chlorine.

So ppm for Bleach is:

ppm = Gallons Bleach * (% Hypochlorite / 100) / Pool Volume (Gallons) * 1,000,000

ppm in lbs

ppm = lbs * (% Hypochlorite / 100) * .125 / Pool Volume (Gallons) * 1,000,000

Hope that helps.