Well Water, Stable FC after Green - rediculous CYA

Apr 13, 2017
Miamisburg, OH
Closed the pool a bit late in the season last year, FWIW decided not to cover this winter.
On Saturday water was 59, got to 61 on Sunday and turned green overnight!
Shocked the heck out of it with cal hypo granules (power powder), I also use calcium hypochlorite tablets in a feeder.
I tend to stay on the low side, as I have troubles breathing and chlorine makes it worse.

I opened last year with a CYA of 50, closed at 40. Opened this year - off the scale.
Testing with a new k2006. Last year I used a 1004 and CYA testing was done at Leslies. I'm wondering if the tests were done correctly :confused:

Combined Chlorine 2.
Free Chlorine 17
6.9ph, 19 drops for acid test :/
TA 2
CH 130
CYA - not on scale, maybe 140-150ppm?

So am I really stuck with drain/refill over 75% of the pool? This will be ridiculously expensive as i'll need a lot of iron out and time on our well.

Water is no longer green after algae crisis, may have to reshock to get it clear or floc.

Any help and advice is appreciated, thank you!

I'm including some pictures, because, well they make everything better!


Mod Squad
LifeTime Supporter
Jul 10, 2012
Tallahassee, FL
I am so sorry :( You have fallen victim to the pool store testing done wrong. The CYA is the test they get wrong most of the time.

Trust your test kit. The pictures are great and show you are correct. Your CYA is too high.

Some areas have a reverse osmosis service that can remove the CYA from the water. It is not cheap so I will let you explore it in your area and see what you think about using it instead of removing and replacing water.

If you keep up the SLAM your pool will clear. Keep the filter running 24/7 so it can do it's job. Keep brushing to get the water good and mixed up.

Let us know what you decide to do.



Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
How did you get a TA of 2ppm? The test reads 10ppm per drop. Should this be 20ppm?

If the TA is 20, the pH is likely much lower than 6.9, both should be addressed right away.

You also need to address that CYA level, it is very impractical to SLAM at such high CYA levels. If your CYA is 120ppm, you would need to maintain a FC of 48ppm.

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Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
Your algae problem needs to be dealt with first then you can deal with iron. I would also say that with such a high CYA level, you need to drain and refill about half the pool. Either one big drain, or multiple partial small ones.

Ok, lemme think... you have a well with iron in the water, right??

You know about the iron... so you know it needs to be removed or sequestered as much as possible, am I getting this right??

Any chance of trucking in replacement water from a source without metals??

Some folks have used homemade devices to try removing the iron... like a big kitty litter bucket filled with polyfil pillow batting to which they cut a hole in the bottom and one in the top for a hose to run in to. The water goes in and the poly batting works to help capture some of the iron. The fill would require occasional replacing. I've also seen where folks have used paper towels in their skimmers to help filter out some iron.

A couple of old threads discussing this problem-
A Tale of Two Filters... and Ugly, Rusty Water.
Iron Filter

Youtube has some nifty video demos of folks working to get the iron out of their water. Check them out.

Yippee :flower:
Apr 13, 2017
Miamisburg, OH
Yippee, I really dont have much iron post filter and softener. Changing about 70% today, will take about 4 days to fill. I will post up my new fill results before adding anything!

Thank you all for your help!
Apr 13, 2017
Miamisburg, OH
I used the pool pump :)
About 2ft of water to go, should only take about 5 more days! The iron isn't bad if I run it through our whole house filter and water softener. I'll check it after we complete the fill, the bleach is pretty good at converting clear water iron into ferric iron that the sand filter picks up. So far I have not gotten any green or iron stains from our water.