Pool a dark green/brown after adding non-chlorine shock


Jul 28, 2013
West Monroe,La
I opened my pool on Saturday. Added metal sequestrant and algicide and let the filter run 24 hrs then added a chlorine float with 3" tablets and started adding a gallon of 12.5% liquid chlorine nightly. I have a SWG but I haven't turned it on yet. I'm on well water, so I try not to add too much chlorine initially on the hopes I can avoid reacting with the metal before it can be filtered out. My pool was fairly clear, just a little cloudy. I didn't have any more liquid chlorine so I put in 3-4 lbs of non-chlorine shock (Potassium Peroxymonosulfate) last night and this morning I woke to find the dark green/brown mess. Is this just the shock reacting with the metals in the water? Or is something else going on? Is there a good way to get this cleared up? Or is it just a matter of waiting for the metal to be filtered out?

Thank you

As of this morning:
FC: 0.44
CC: 0.38
PH: 7
TA: 126
CH: 26
CYA: 38


Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome to another season! :wave: Well, by the looks of the water and your very low FC level, I suspect you have not only an iron problem from the well, but also an algae issue. As you probably already know, when that happens, you have to treat for algae first. We know that will aggrivate the iron. Just can't get around that. But you have to remove the algae by following the SLAM Process completely until you pass all 3 criteria first, then you can let the FC drop to normal and treat for iron. During this time, don't bother with sequestrants and certainly no algaecides that only add more metal (copper). Use regular bleach or pool chlorine (same thing) for your sanitizer.

Also review the Stains in Your Pool - Trouble Free Pool page and let us know if you have any additional questions.