SLAM - FC too high

[Pirogi]

I found green algae on the bottom of the pool yesterday, so I went and got some bargain bleach last night. This is the first time I've SLAMed. CYA was 70, shock FC = 28.

Somehow I made an error using PoolMath, and I thought I was supposed to add 633 oz 8.25% bleach instead of 605 oz. Five gallons is 640 oz, so I just dumped 5 gallons in. Apparently the bargain bleach was more concentrated than 8.25% as well because raising FC from 6.5 to 30 should have taken 661 fl oz, which is more than I added.

I tested just now, an hour after adding the bleach, and I'm at FC = 38. Is this a problem for my pool's integrity? Do I need to drain and add water? Or just monitor and let it fall naturally?

 

[JoyfulNoise]

Your pool will be fine. Just let it come down naturally on it own.

 

[YippeeSkippy]

Just monitor and let it come down to the desired SLAM level and keep on from there. It shouldn't be a problem.

 

[domct203]

I would guess the error is the pool capacity. When I enter a 27 foot round pool with 48 inches of water depth into the "Estimating Pool Volume" section of pool math I get 17,100 gallons.

While it's not a large difference, it will throw off your calculations.

For example, in 17,100 gallons it takes 595oz of 8.25% to go from 6.5ppm to 30ppm. In 18,500 gallons it would take 644oz.

As mentioned, the pool will be fine, let it drift down naturally. According to pool math, in 17K gallons it takes 25oz of 8.25% bleach to add 1ppm FC.

 

[singingpond]

And do plenty of brushing while you have the chlorine at this (unintentional) high level, if you have the time. That will assure that you are exposing the algae to the chlorine in the most effective way (brushing breaks down a protective film or layer than can be formed by some organisms when they settle/grow on a surface, such as the wall or floor of your pool).

 

[Pirogi]

Thanks! I had it set at 4.5 ft depth. I don't remember why I chose that instead of 4 ft.