Why isn't my chlorine sky high?

[Slippery]

The pool was a VERY deep green. I dumped an entire gallon of 10% "pool" bleach over the course of 3 days. This morning I did half a bag of HTH shock/calcium hypochlorite (bag says for 13500 gallon pool. mine is 4000). Just tested it at 5pm using the DPD test in the TF-100 test kit and got a 1ppm. The green went away after the first half of the pool bleach. It's blue but very cloudy. Pump has been running 12 hours a day since last week. It had a lot of leaves in there but I wasn't able to scoop most of them out until I could see them.

I'm worried the chlorine level could be so high that the standard 5 drop test can't catch it (would it be clear or a bright yellow if it is off the charts?) and I am damaging something. Is it possible there is that much organic material in there? My CYA was at near 0 when I started so I added enough to get up to 60. The water is 52 degrees I was getting the sense that it would take a while to dissolve. It's been 48 hours. Have not tested CYA since. Was thinking about dropping the rest of the HTH shock bag when the sun goes down.

 

[jimbethesda]

A few things.

Algae eats chlorine, so not a surprise it gets used up quickly.

Which chlorine test are you using? You say the one in the TF 100, but you also say “standard 5 drop” and mention the color yellow. You want to use the FAS-DPD test. Put DPD powder in, it turns red if it has any chlorine, then count drops of reagent until it’s clear to see how much free chlorine you have.

What’s your calcium level? Probably don’t want to add more. Liquid chlorine is best. You need to follow the SLAM process.

 

[jimbethesda]

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

Waiting until the sun goes down just let’s the algae grow more. The M in SLAM stands for maintain. You want to maintain the shock level of chlorine until the SLAM exit criteria is met.

 

[Newdude]

Hey Slippery !! A few big things stick out to me.

1) the test water needs to be room temp for CYA. Don't trust it at 52 degrees because you can't take CYA out if you add too much.

2) at 4000 gallons its about as easy to dump and start over. If your water is cheap it's a no brainer, and if your water is expensive it's still not *that* costly for the amount of aggravation you will have by fighting the algae. It can be done and we do it all the time. But its a process and it takes effort.
3) once the water is blue/blueish again, you've basically killed the bulk of the algae but still need to filter it out of the water. If you run the pump 12 hours a day it will take twice as long to clear the pool. Its up to you and as long as you maintain the SLAM FC, there is no harm in it taking longer, it's just frustrating longer. I'd run 24/7 until it's done. Keep an eye an your filter pressure and backwash anytime your PSI rises 25%. Sand filters usually take many backwashes to clear a swamp.

Keep us posted