Green pool with copper issues

[Biggietuna]

Hey all! My second season with this above ground 16k gal pool. Sand filter.
my test results today:
Free chlorine 4.6
Combined chlorine 0.8
Ph 7.4
Total Alkalinity 110
Calcium Hardness 120
CYA 70
Water pretty clear but green tint.
waiting for chlorine to come down so I can add metal out and turn it blue again.
I did the slam last week and my combined chlorine went down to 0.4 but now I’m back up to 0.8. Do I need to SLAM again? Maybe my reading was wrong? I double checked today’s CC reading. I’ve been waiting for my chlorine to drop to around 2 and use polyquat 60 along with metal out. In the meantime, pool math app is telling me to add stuff. Help me please you geniuses.

 

[Texas Splash]

Welcome to TFP! Let's first discuss why you are assuming it's copper. Do you use a mineral system i.e. Frog) or have you added copper-based products in the past? Or are you on a well which would probably mean iron instead? Have you tried rubbing a Vitamin C tablet on a stained area?

 

[Biggietuna]

Hey thanks! Last year I used an algaecide with copper and it turned a foam green. Went to the pool center. They told me it was from the copper. I am on a well. I probably have iron as well. I used a thiosulphate, lowered my chlorine and added metal out and it did turn the water turn a more appealing color. This year, as soon as I raised the chlorine and ph my water turned green again. So I continued the SLAM process til it was successful. But now as I’m waiting for the chlorine to get low enough to add metal out and use a polyquat60. I have done a test that returned a higher combined chlorine. 0.8

 

[Texas Splash]

I see. Well, copper is a problem and generally water has to be changed to lower copper content below 0.3 ppm. If it's not that high you might be okay. As for iron, at times it can be filtered via polyfill. The trick now is determining what is setting-off the water color changes - iron or copper. Now that your SLAM is complete, I would ensure the pH is no higher than 7.5 and balance the FC to your current CYA as noted on the FC/CYA Levels. Hopefully you have a TF-100 or Taylor K-2006C test kit for all of this as testing is extremely important in your situation. By the way, don't forget to update your signature so we can see all of that info. See my sig as an example.