Water turns green when I had water to pool

Seems like I have a leak in my pool. When I had water from my surface well overnight, my pool water turns green. Then I shock it and its back clear within 2-3 hours.
My well water as 2-3 ppm of chlorine and a PH of 7.0.
Why is that? Anything I can do ? Maybe I could shock it before but I cant run the pump because the water gets too low.
Confused.

It is very unusual that a private well would have any chlorine in it. Where are you getting the test water from? Is there some kind of chlorine source in the well that's used for disinfection?

Also, can you have your well water tested independently? Well water is typically full of metals and the green color could be from copper or some other metal in the water. It could also be algae if the water in the well is stagnant. Do you use this well for house water or is it a secondary water source for the pool and landscape irrigation?

It does have chlorine at 0.5 FC and a neutral ph of 7.0. We use this well for our poultry farm and we treat our water.

OK, I think I get it now. So you use your own well water (pretreated with a little chlorine) to refill your pool's daily evaporation loss.

I'm going to guess that, while your well water is safe enough for the purposes of using it on your farm, it is not really clean enough for pool fill water. Likely what your seeing is green coming from a minor algae bloom caused by the well water and then you kill it with shock. Not the best thing to do as the shock is going to build up either excess calcium in your water or excess cyanuric acid (stabilizer) depending on the kind of shock you use (unless you're using straight bleach which is always the best).

So I think you need to pretreat the water BEFORE it goes in your pool. One way to do that would be to use a 50 gallon barrel or large container to fill with well water and then hit it with a shock level of chlorine to kill anything in it. Then after the water is treated, you can then let it into your pool. You're basically doing that now but your pool is acting as the "pretreatment" container and that's just not good. There's lots of ways to create these types of treatment barrels using large plastic drums and making hose connections into and out of it (one supply hole in the middle and three drain holes in the top). You can get fancy with ball valves and hoses and put all sorts of bells and whistles on it but the idea is the same - treat the water with high FC levels BEFORE it goes into your pool.

If you were having metal problems, then shocking your pool water when it was green would cause all kinds of staining which is not the case.

Not sure that there is any algua in the well water as its already pre treated in a 10000 gal holding tank.
If I would shock the pool before adding water would that help? I always use straight 12% chlorine I buy in 45 gal drums.

Well, that is certainly strange.

Instead of playing the "20 Guesses" game and going back & forth on speculation, I think the appropriate thing would be for you to post a complete set of water chemistry data for both your pool water and your fill water. Having been on this site, you know that we all prefer test results from a Taylor K-2006 test kit. If you can post the full suite of test results and update your signature with details about your pool (size, equipments, etc), then I think I and other folks here can help you better. Short of that, all it will be is conjecture...

I use Taylor K-2006, cannot change my signature?

Here are my pool water #.
Fc 2
Ph 7,5
TA 90
CH 120
CYA 40

My well water is FC 0.5-1.0, ph of 7.0

Thinking if I shock the pool before adding chlorine, would that prevent that?

Quote:

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Originally Posted by Skymarc

I use Taylor K-2006, cannot change my signature?

Here are my pool water #.
Fc 2
Ph 7,5
TA 90
CH 120
CYA 40

My well water is FC 0.5-1.0, ph of 7.0

Thinking if I shock the pool before adding chlorine, would that prevent that?

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Ok, I think I see the problem now - your pool water has far too little FC. For a CYA (stabilizer) level of 40ppm, your MINIMUM FC level should be 3ppm. And that is the LOWEST it should ever go in any 24-hour period. In fact, you should probably be running your pool's FC somewhere between 4-6ppm to maintain proper chlorination.

As well, I don't believe your well water is sanitary in the sense that it is probably ok for the purposes of using it on the farm, but I doubt you are able to maintain a constant 1ppm FC level especially without any CYA in it. In fact, I would be willing to wager that your well water falls below 1ppm FC and that algae and/or other pathogens are able to survive in it. Municipal water supplies can get away with 1-1.5ppm of FC with no stabilizer because the water is highly treated at the source (chlorine, ozone/UV, microfiltration,etc) and runs through relatively clean piping before it reaches your home. An underground well is no where near as clean.

So, you're taking suspect well water, adding it to your pool and DILUTING your already way too low pool FC to a level where algae can bloom. Then you shock your pool and kill the algae bloom you started with your fill water.

So, I would recommend two things -

1. You need to RAISE and MAINTAIN your pool FC at a higher level (4ppm to 6ppm);
2. You should shock treat your fill water BEFORE dumping it in the pool

Other PF'ers can chime in if they think I'm off base....