how much shock is too much?

[can-opener]

I have a 18,000 vinyl pool with algae. Six days ago (before vacation) I shocked the pool raising the cl to over 20-ppm with a pH around 7.4. This morning, pool has more algae then before I shocked & CL was 5-6-ppm. Is there an algecide product I should try or am I not raising the cl high enough when shocking?

I replaced the sand in my filter a couple weeks ago, after I converted the pool from Baqucil with zeobrite (zeolite).

Total alk = 200
CYA = is a little low

How do I get rid of this algae?

[larry2338]

You have to maintain your chlorine shock level consistently for as long as it takes to kill all of the algae. May take a couple of days, may take a week, but you can't let your chlorine level drop below the proper shock level for even 24 hrs. or you'll never get rid of the algae.

"CYA = is a little low" isn't going to cut it. Your correct chlorine shock level depends directly on your CYA level. Depending on your actual CYA reading, 20ppm may be way too high for your pool or it may be way too low.

Get an accurate CYA level test and then check Ben's Best Guess table to determine what your correct shock level is. Maintain that shock level (testing 2-3 times per day if possible) as long as it takes to kill all of the algae.

[can-opener]

Thanks Larry! I appreciate your advice.

[justgrapejuice]

Get an accurate CYA level test and then check Ben's Best Guess table to determine what your correct shock level is.

Is there a way to get another verision of Ben's Best Guess Table? I do not have a PC only Mac's in the house, and I see this is an executable file.

Thanks...

[waterbear]

You are confusing the best guess table with bleachcalc. the best guess table is here
http://www.poolforum.com/pf2/showthread.php?t=365
Bleachcalc will not work on a mac.

[mbar]

Use the info in this chart to help you figure out what levels of chlorine you need to maintain in your pool based on the amount of CYA (cyanuric acid, also called stabilizer) that you have in your pool. (FC = free chlorine)

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

[justgrapejuice]

You are confusing the best guess table with bleachcalc. the best guess table is here
http://www.poolforum.com/pf2/showthread.php?t=365
Bleachcalc will not work on a mac.

Since there is not a Bleachcalc for a Mac, is there something that I can use to determine my needs?

Oh, BTW thanks for the best guess table info.

[waterbear]

1 gallon of ultra bleach will raise 10000 gal approx 6 ppm
1 gallon of regular bleach will raise 10000 gal approx 5.25 ppm
Call your pool 20000 gallons to make the measurement easier so I would add enough to keep the pool at about 12-15 ppm until the algae is gone.
another way to look at it is 2 oz of ultra bleach will raise 1000 gallons about 1 ppm so every 36 ounces (call it a quart to make it easer) will raise your pool just about 1 ppm or slightly less.
These are approximations but should be close. Test the water and make adjustments accordingly.
Hope this helps.

[justgrapejuice]

Thanks so much, i really love this site. Everyone is very helpful and quick to respond!

[justgrapejuice]

Also, are there test kits to test the chlorine levels above the 3.0 mark? Also, what is the method you are using to calculate to check the higher Chlorine levels?

At what level would the chlorine level be too high to swim in?

I have a above ground doughboy 13,000 pool, will the higher levels when I shock be okay for the liner?

Thanks