Pool is green, but free chlorine is high and combined chlorine is 0

fenway

New member
Sep 2, 2021
2
Southern New Hampshire
Pool Size
25000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hi, everyone,

First time poster but long-time learner and lurker on the forum. My partner took pool school and we've searched all the forums and can't figure out why our pool is still green. We bought a house and started opening the pool on 8/17. It was a swamp, but all the equipment was properly winterized when it was professionally closed last fall. Sand filter, pump is one year old. Our first few days were kind of wasted with not adding nearly enough bleach, not vacuuming early enough, etc. We got everything together and started SLAMing the pool about 11 days ago now. pH (7.6) and Alkalinity (90ppm) have stayed stable. Our water is very soft -- no copper or iron at all. Phosphates come in around 38ppm.

Here's where we're getting caught up: our total chlorine levels have been consistently ~30ppm+ and stabilizer under/around 45-50ppm. Somehow combined chlorine keeps coming in at 0ppm. We thought maybe we had a defective test kit so we brought a sample to our local pool store and their results were the same -- free chlorine at 33.21ppm, combined chlorine at 0ppm.

If we're keeping these numbers stable, running the pump/filter 24/7 and backwashing when needed (1-2x/day), brushing the pool regularly and already vacuumed all debris... Why is the pool still a green, cloudy mess? Some days it's a duller green, other days it's more neon green. It's certainly not as murky as when we first opened it, but I haven't seen any noticeable change at all in the past 6-7 days.

We were hoping to open it so late in summer just so we could see the bottom, have peace of mind that everything works, and maybe take a dip or two before needing to shut it down for winter...
 

fenway

New member
Sep 2, 2021
2
Southern New Hampshire
Pool Size
25000
Surface
Vinyl
Chlorine
Liquid Chlorine
Welcome to the forum!
How are you testing your pool water chemistry?
You need to follow the SLAM Process.
I suggest you read ABC's of Pool Water Chemistry
Thanks for the warm welcome! We're testing with the Taylor K2005 kit and I'm already familiar with the water chemistry terms and what's ideal. We've been following the SLAM process for about 11 days, testing roughly 3 times a day. Free chlorine has staying in the 30-35ppm+ range, and the other numbers have held constant. I'm primarily confused why the ample amount of free chlorine doesn't seem to be doing anything to counteract the algae (or whatever is making the pool green).
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,835
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It is not possible to follow the SLAM process without a FAS-DPD test for FC. Your kit does not have that test. The K2005 cannot test FC above 10 ppm.
 

V___25

Gold Supporter
May 30, 2020
237
Central PA
Pool Size
24000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hello there! Your signature says you have a TF-100. Can you please post a full set of results from your TF-100? Since it was green when you bought it, it's possible the prior owners used stuff that added copper to that water. Did you have the pool water tested for metals? Can you post some pictures of your pool?
 
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Mdragger88

Bronze Supporter
Jun 1, 2018
3,321
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
The words “neon green” are really standing out to me. Pics would be extremely helpful. Also is there another/different pool store you could get metals tested at?
Also SLAM Process fc level for your cya of 50 is 20ppm - going higher just wastes chlorine & risks damage to surfaces, equipment, & swimmers.
 
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