Water is Tinted Yellow/Green

[crokett]

This is season #3 with my pool. The first season it took a month to figure out the water was colored because of the metals in my well water. I finally cleared things up with a product called Metal Free. Last season when I filled the pool I added the Metal Free, let the pump run overnight, shocked it AANND I had discolored water again. It took a couple attempts, some money and a different product (Sequa-Sol) to clear it up. This season I filled the pool this week, got the pump going for several hours, added the Sequa-Sol, let that circulate overnight, shocked it this morning and a few hours later I had discolored water again. The water is clear, just tinted. I put some Metal-Free in a few hours ago - doubled the dosage rate on the bottle - but am not hopeful. My experience the first season was the pool place (at least the one I went to) could test for metals but not recommend a specific product for my water. So some questions

Assuming the water is still colored tomorrow morning, what is the next step? Is there anything else that can cause this? If I get the water tested, is there a specific product I can use based on the amount/type of metals in my water? Why would the fix change season to season? I would think a chelating agent/sequestrant should be consistent.

Thanks for any suggestions. I am an engineer and given an input, expect the same output every time. This is frustrating.

Current levels:
FC: 0 (it is all being used up by the metals)
AK: 130 - it has come out of the hose every season at that level
pH: 7.4 - working to raise it
CYA: 20 - the CYA is still dissolving. I hung a sock in the strainer basket last night.

 

[JasonLion]

Chlorine does not get used up by metals, it gets used up either by algae or by other organic contaminates in the water. If you just opened and the CYA level started lower that it was last year, you probably have some ammonia in the water. Ammonia is burned off by adding chlorine, you just need to keep adding chlorine until you can maintain an FC level overnight.

The amount of sequestrant you need depends both on the size of the pool and the metal levels in the water. You might have higher metal levels this year than you had last year, which might be why the sequestrant isn't working the way you expect it to. The usual rule of thumb is that you need the dose of sequestrant recommended on the bottle for each 1 ppm of metals in the water.

ProTeam's Metal Magic and Jack's Magic the Pink Stuff (regular), the Blue Stuff (fresh plaster), and the Purple Stuff (SWG) are some of the top sequestrants. You can also find many other brands with similar products, some of which are noticeably less expensive. Sequestrants based on HEDP, phosphonic acid, or phosphonic acid derivatives are the most effective.

 

[crokett]

Chlorine does not get used up by metals, it gets used up either by algae or by other organic contaminates in the water. If you just opened and the CYA level started lower that it was last year, you probably have some ammonia in the water. Ammonia is burned off by adding chlorine, you just need to keep adding chlorine until you can maintain an FC level overnight.

Sorry, forgot to mention, the CYA started at 0. I drain the pool and take it down for the winter. If there is ammonia in the water it is naturally occurring. 'Used up' is the wrong word, or else I am misunderstanding. I thought the chlorine was reacting with the metals and when it does this it does not do the job of killing things in the water. I would be a lot less worried about colored water if the chlorine was still killing things. The first year you guys helped me clear up a bad algae bloom and I never want to go through that again.

I will get the water tested for the metal PPM. The dosage rate on the bottle is 32 oz per 20k gallons. That works to 1.6oz per thousand. So should I add 1.6oz for each 1PPM?

 

[JasonLion]

Metals can turn neat colors when you shock the pool, and that can use up a small amount of chlorine, but for the most part metals don't interact with chlorine at all. Some brands of sequestrant also use up a little chlorine when you first add them, but again not all that much.

1.6 oz of sequestrant per 1,000 gallons per 1 ppm, or fractional part, of metals. Using a random example, if you have 10,000 gallons and 2.5 ppm of metals then use 1.6*10*3 or 48 oz. The 10 is for 10,000 gallons of water, and the 3 is 2 full ppm of metals and one fractional part of metals.

By the by, my guess is your pool holds more than 3,400 gallons. My guess is more like 4,600 gallons. That assumes a 15' round pool with 3 1/2 feet of water in it.

 

[crokett]

Thanks for the clarification on chlorine reacting with the metal. I feel better and will keep feeding it chlorine. I will get the water tested to find the PPM and correct the dosage.

 

[crokett]

Hi Jason,

A somewhat belated thanks. I got the water tested and got some more chelating agent. I added more according to your formula. and the water cleared right up. The math was just about spot on 8). I will remember it for next year.

 

[JasonLion]

Great!