Fill after resurface, clear Yellow/Green Water

[richguy]

Last night we refilled our pool after a fiberglass resurfacing, this morning we added chlorine and very quickly the pool turned green. Water is clear green and we can see all the way to the main drain (See attached photo)It is a diving pool, so that is 9+ feet of water. Given that I don't think we are dealing with algae (The two dots at the bottom are diving dolphins thrown in by excited kids, and the darker part is just in shade.)

Based on what I have read here, it sounds like we must have had metal in the water, probably (based on color) copper. I cannot get Metal Magic or Magic Jack's in town anywhere, but I can get HTH Metal Control at Home Depot.

Is that a reasonable solution? I realize the puts the metal in solution and will have to be managed over time. What FC, PH levels should I be shooting for before adding this? Right now FC is over 6 (Overshot badly due to reading chart wrong) and PH is 7.2

 

[duraleigh]

What you are seeing is iron precipitating into solid form. The chlorine causes it to precipitate into a brownish yellowish color combined with the blue water gives it a final color of clear green.

Over a period of days, you will filter out that iron (and some of the iron will re-dissolve) and your pool will return to blue. Another sudden dose of chlorine will likely cause it to turn back green again so be judicious with your chlorine dosages.

Can you post test results so we can suggest where your FC should be?

The very most common source of iron is filling from a well.

 

[richguy]

Thanks very much for he response and information.

Current test results are:
FC 2
CC 0
CYA 0 (using dichlor for chlorine until I hit target of 40)
TA 160

results from TF 100 test kit. Will do another full panel tomorrow.

I will hold off on Metal Control for a couple of days to see if the color improves.

Also, we filled from city supply, not a well but maybe there was metal in the supply. Targeting 3 FC until we get over 20 CYA.

 

[duraleigh]

Don't let your FC go any lower. keep it 2-4 ppm. I am not a fan of dichlor but it works and that's your call.

Since your supply is going to have iron, you may as well resign yourself to a sequestrant. Keeping your FC low and adding it SLOWLY will help but the sequestrant may be easier.

Iron in pool water is one of the most nagging problems we see. What is your current pH and tA?

 

[richguy]

So, after a couple of days of filtering, and maintaining FC @2-4 and PH @7.2ish, the green color is completely gone. We are clear blue and sparkling. At one point a ring formed around the water level, but that was quickly dispatched with cheap Vitamin C tablets. We are excited to have our pool back and ready to swim.