What caused my new pool water to turn green?

@aumfc, let's try to recap a few things:
1 - You're on a well and that water supply has a high iron content. I suspect the builder knew that and "tried" to add a product to control a reaction between iron and chlorine, but that's not fool-proof.
2 - Ideally, you want to remove as much iron as possible to avoid such reactions (hence the polyfill) or replace water with fresh trucked-in water that has no iron.
3 - The higher the iron content, the more potential for iron staining and reaction to chemicals. Pool owners on well water MUST control the FC and pH as much as possible. When the pH and/or FC get too high, it causes a reaction with the iron.
4 - If you try to add a sequestrant product now, you will cause iron to bind with water which will help to prevent additional staining, but will also reduce the effectiveness of filtering with polyfill.

For now, I would encourage you to first focus on completing the pool start-up process. The health of your plaster (with proper testing) is a priority. You can address the staining later. You can review all the info we provide to determine (later) how you wish to address and manage the iron in the water. Polyfill filtering, frequent use of sequestrants, or an Ascorbic Acid treatment later followed by a water exchange are examples. The fall may be an idea time to consider an AA treatment. For now, continue to filter as much iron as you can with the polyfill. The more iron you remove now, hopefully you'll see less staining and reliance on sequestrants. Success stories are out there, much like that example (link) provided above. You can do it.
 
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@aumfc, let's try to recap a few things:
1 - You're on a well and that water supply has a high iron content. I suspect the builder knew that and "tried" to add a product to control a reaction between iron and chlorine, but that's not fool-proof.
2 - Ideally, you want to remove as much iron as possible to avoid such reactions (hence the polyfill) or replace water with fresh trucked-in water that has no iron.
3 - The higher the iron content, the more potential for iron staining and reaction to chemicals. Pool owners on well water MUST control the FC and pH as much as possible. When the pH and/or FC get too high, it causes a reaction with the iron.
4 - If you try to add a sequestrant product now, you will cause iron to bind with water which will help to prevent additional staining, but will also reduce the effectiveness of filtering with polyfill.

For now, I would encourage you to first focus on completing the pool start-up process. The health of your plaster (with proper testing) is a priority. You can address the staining later. You can review all the info we provide to determine (later) how you wish to address and manage the iron in the water. Polyfill filtering, frequent use of sequestrants, or an Ascorbic Acid treatment later followed by a water exchange are examples. The fall may be an idea time to consider an AA treatment. For now, continue to filter as much iron as you can with the polyfill. The more iron you remove now, hopefully you'll see less staining and reliance on sequestrants. Success stories are out there, much like that example (link) provided above. You cancousins.

Hey everyone. The guys that built the pool maintain it for 4 weeks. They came out and put metal free in it. Didn't ask so I guess it's part of the build service.

Anyway, water was clear Friday and Saturday. We had a storm last night and woke up to this.

20230430_170002.jpg

This is a different color than last time. Nothing added to the pool other than rain water between yesterday and today. The water is still very clear just green again.

They also had chlorine tablets in it that are pretty much gone now.

I tested my iron with an electronic colormeter-thing, after going through my filter and it's 0.09ppm. But I don't think any of it got in the pool last night. I turned off my auto fill just in case, though.

I think the iron originally got in due to trying to fill it non-stop from the well for over a week, and possibly getting into an iron level the filter system couldn't handle.

In any case, ideas on how this could happen?

My $200 test kit you guys recommended should be here tomorrow, fyi.

Thanks!
 
Hey everyone. The guys that built the pool maintain it for 4 weeks. They came out and put metal free in it. Didn't ask so I guess it's part of the build service.

Anyway, water was clear Friday and Saturday. We had a storm last night and woke up to this.

View attachment 487496

This is a different color than last time. Nothing added to the pool other than rain water between yesterday and today. The water is still very clear just green again.

They also had chlorine tablets in it that are pretty much gone now.

I tested my iron with an electronic colormeter-thing, after going through my filter and it's 0.09ppm. But I don't think any of it got in the pool last night. I turned off my auto fill just in case, though.

I think the iron originally got in due to trying to fill it non-stop from the well for over a week, and possibly getting into an iron level the filter system couldn't handle.

In any case, ideas on how this could happen?

My $200 test kit you guys recommended should be here tomorrow, fyi.

Thanks!
I wouldn’t go too far speculating on what it is until you test the water. If the pool store tested for metals and it came up empty, then it’s likely algae. The test strips are garbage so don’t waste any brain energy on anything they show. The pool store test for anything other than metal aren’t any more reliable than the strips.

Any stains need to be addressed after the water is clear. Unfortunately your pool guys didn’t do you any favors. You might ask them what they did to make it easier to fix.
 
That’s a bright green 😳
Until your kit comes do as Pat said & replace the polyfill.
When it comes, do all the tests & post your results.
We’ll be here!
 
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