Green Tint after Cooling Hot Pool Water with Well Water

[davethomaspilot]

I have an intermittent problem with my IceBreaker heat pump.

The heat pump can be used to cool the pool water in addition to heating it. But, the valve inside the heat pump that controls heating versus cooling mode sometimes sticks in heating mode when it should be cooling. But, that's another story...

That's what happened Friday night. We turned the heat pump on in cooling mode so that we could get the pool down to a nice refreshing temperature for a party Saturday night. But, when I checked the pool temperature Saturday afternoon around 2:00 pm, it was 100F! Not good!

While I worked on getting the heat pump valve unstuck, I decided to start cooling the pool using well water. I back washed about 6" of water from the pool and started refilling with cool water from the well.

Within an hour, the pool water was tinted green. Clear, but definitely a green tint.

FC, PH, and TA were right on target--same as they've been for six months with no issues. CC was zero.

I have an iron test kit, and tested the pool water, but saw 0 iron. Copper is the same residual .1 ppm I've had since last winter when I stopped using an Copper Ionizer.

I saw a post that DuraLeigh responded to that he sees something similar every year when he opens his pool and adds well water. He said the tint goes away in a couple of days.

I decided to shock the pool to rule out organics (but CC is zero already) and run to Lowes/HD to get some DE to add to the filter. The best theory I have is that the well water does have iron, but for some reason it's not detected by the Taylor test kit.

Now I recall that when we first filled the pool, we used two truckloads of water and I finished filling the pool with well water (maybe the last foot, IIRC). I remember there was a green tint to the water. At that time, we weren't sure if that's just the way the water would look with our Pebblecoat, so we didn't worry about it.

Anyway, I plan to shock (not SLAM, since CC is already 0) it for 24 hours and add the DE and see what happens. I'll report what happens.

 

[Isaac-1]

I agree it sounds likely you have a metals issue, unfortunately the metal detection kits can be a bit hit or miss

 

[duraleigh]

The well water had iron but when you put it in the chlorinated environment of your pool, the iron precipitated out and turn the pool greenish-brownish.

It will go away if you just leave it alone and run the pump 24/7. It will then filter out or go back into solution and your pool will clear up fine.

Adding more chlorine (I assume you have adequate but you don't post test results) may make more iron precipitate and make it take longer to get clear.

 

[davethomaspilot]

The tint was already greatly reduced by the time I got home with the DE.

I did add chlorine to get FC around 6.0 (CYA =0), but I doubt the FC is making the difference since CC remains zero.

TA = 70
PH = 7-3 to 7.4

So, it does seem it's going to be color free in a day or two, even with the FC at shock level.

I'll check the FC at sunset and again tomorrow morning. If there's no decrease in FC, I'll let it decay back down to my normal target level.

So, I guess the iron test kit is pretty much worthless? Maybe I should just test the well water standalone? Maybe it will be dectable before the chlorine causes it to "precipate"?

Thanks!

Dave Thomas

 

[duraleigh]

Maybe I should just test the well water standalone? Maybe it will be dectable before the chlorine causes it to "precipate"?

Exactly.

 

[PAGirl]

Are you planning on getting some CYA added soon? (Unless it's an indoor pool....)

NVM, I read where you purposefully keep it low.

 

[davethomaspilot]

I figured I start another thread on CYA in the "controversial" forum.

I have an automatic chlorinator and acid dispensor (Intellichem). With automatic chlorination and PH control, I don't see the point of using CYA.

With zero CYA I have much less chlorine depletion in absolute terms and there seems to be no problem maintaining target FC even in full sun hot weather. At least, that's the theory based on this forum's posts and technical information.

Without CYA neutralizing the chlorine's sanitation capability, it also takes much less chlorine to SLAM.

I understand why CYA is needed with a SWG with limited chlorine generation capacity, but I see no advantage with an automated chlorinator.

0 CYA has worked trouble free for me all summer.

 

[davethomaspilot]

Pool was completely back to normal this morning. I have before/after pics on my phone. I'll post once when I'm online with my phone.

FC depletion overnight was 3 drops, from 4.0 ppm to 3.4 ppm. CC wasn't the usual zero pppm, but .6 ppm. So, I guess the results are inconclusive on whether organics were playing a factor in the green tinting.

But...

The water turned green in less than a hour after the well water was added. Can that happen that quickly with some organic contamination in the well?

If it was metal, where did it go? Did it get filtered out? If it's still there, why no green tint now? It's not like the FC went down--it's higher. PH and TA aren't significantly different either.

I worry, because the pool autofills with well water. Should I worry?

Thanks!

- - - Updated - - -

Haven't tested the well water yet either. Will do that tomorrow morning and post results.

 

[davethomaspilot]

Sunday morning, green tint:



Monday morning, back to normal. That's when picture was taken, but it was actually back to normal late Sunday afternoon:

 

[davethomaspilot]

Tested the well water, but still no detectable iron using Taylor K-2176.

 

[PAGirl]

Based on the drainage the steps being hard to see it looks a Little cloudy in the tinted pic.

 

[Vickery]

Is your finish blue? Because topping my pool off with well water will result in a pale yellow tint when sunlight hits it in a white bucket...but looks pale green due to the blue liner. A full fill with well water is a different story (looks like a red clay mud hole.) It takes about a day for the precipitated iron to be collected by the filter on a top off.

 

[davethomaspilot]

No, there's no blue in the "Black Perl" Pebble Tec. (That's not my pool, just the Pebble Tec color I use on the left.



Thanks for the thought, though.

One other consideration--the well is 400' deep. When I used the well water to cool the pool, perhaps the well was drawn down to an unusually low level. Maybe that causes a different set of minerals in ingress into the well water.

The well water has no color that I can discern in a bath tub full. It does get "stinky" (sulpher smell) once or twice a year. I disinfect it with a 6 quarts of bleach when that happens. But, it looked and smelled normal when this incident occurred.