Chlorine Disappearing Fast

[mobileguy]

20 Chlorine Bottles
12lbs of Shock

FC: 3
CC: 3
CYA: 40
TA- 80
CH- 280
PH-7.4

Pool set for 2 years by a previous owner. When opening the pool it had a tint of green in the deep end. I've shocked the pool 3 times and held 15-20FC for more than 24-48 hours adding chlorine in on the hour. Vacuuming pool every morning when I see what I think is a bunch of dead algae on the bottom. The pool now is clear but not holding FC very well. I've been trying to keep FC at 5-8, however it disappearing. Ran the over night test and FC dropped from 5ppm to nearly .5ppm.

Not sure what to try next?

 

[PaulR]

Keep FC at shock level until the FC holds overnight, CC is 0.5 or less, and the water looks good. Currently you are only 1 for 3; not done yet!

You probably don't want to use any more powdered chlorine; your CYA and CH are both to a point where it's probably not advisable to raise them any higher, and nearly every kind of powdered chlorine will raise one or the other of those parameters. Stick with liquid.
--paulr

 

[JMarch]

as long as your CC is over 0.5, it'll keep demanding free chlorine because it's probably still burning out the chloramines.

 

[JasonLion]

Vacuuming up as much of the dead algae as you can will speed up the process.

 

[mobileguy]

I heard with high CC the best way to burn it off is to let the pool get a lot of Sunlight?

 

[PaulR]

Yes, sunlight will help a lot; if you have a cover, leave it off. But you still need to maintain your FC until you pass the overnight test.
--paulr