Green Tint

[09659]

How can the green tint be removed?

The surfaces are not slimey.

I inherited it this way (as a service company, I don't own it).

 

[PJ]

Does it look that way when you drain it? If you haven't drained it yet I would recommend doing so, scrubbing the inside with a bleach solution, re-filling, soaking the cartridges in a solution, and shocking it. If it seems to be a stain on the shell...I would try a stronger bleach solution on an area and see if that helps.

 

[09659]

No, it does not look that way when it is drained. I was told it turns green a few days after refilling.

 

[PJ]

It sounds like you need a good shock then...to get rid of any algae that might be in the plumbing or filters. Are you keeping sanitizer in the water at all times? ...and are you keeping the water balanced?...Do you keep it covered?

 

[linen]

Welcome to tfp, 09659

That looks like it could be metals in the fill water (green tint could mean iron or copper in the water). If it is algae, you would typically see some amount of cloudiness...which I am not seeing.

How are you chlorinating/sanitizing the water? If you use chlorine, is it clear until you add it?

 

[09659]

Are you keeping sanitizer in the water at all times? ...and are you keeping the water balanced?...Do you keep it covered?

I inherited it this way (as a service company, I don't own it).

If you use chlorine, is it clear until you add it?

No, it was never clear, and never slimy.

I drain and refilled it. No more green.

Out of curiosity, would an ascorbic acid (Vitamin C) treatment have removed the green tint?

Thanks

 

[JasonLion]

No, vitamin C would not have helped. Sequestrant would have helped, but that is not worth using on a spa.

 

[09659]

Why can green indicate iron? Doesn't iron oxidize as a reddish brown color and copper as green?

Ascorbic acid can treat staining on surfaces, but not handle the metals in the water, correct?

I thought I read that sequestrant only works as a preventative agent, but not after the metals have oxidized. Is this the case?

Thanks

 

[JasonLion]

Iorn oxidizes yellow, but yellow plus a blue pool surface and/or the usual blue tint to the water looks green. In rare cases you can actually see it as yellow.

AA converts the state of the iron so it can dissolve, but it is already dissolved when it is tinting the water. Sequestrant binds to the iron/copper and that prevents it from coloring the water or depositing as stains. Sequestrant can't lift stains by it's self, it only binds to metals already in the water.

 

[09659]

Sequestrant binds to the iron/copper and that prevents it from coloring the water or depositing as stains.

Can the sequestrant bind the iron and copper after they have colored the water?

 

[chem geek]

I think that the confusion for iron color comes from the color of ferric ion in water (which usually comes from ferrous ion in well water that is oxidized to ferric ion by chlorine) which is yellow* compared to that of ferric oxides-hydroxides aka "rust" which is orange-reddish though can range from yellow to red or darker red depending on the specific composition. Ferric ion is also fairly insoluble so not much of it will remain in the water -- it will tend to stain or precipitate and get caught in the filter. Unfortunately there isn't a reliable way to make it go one way vs. the other. There are some procedures that try and raise the pH, chlorine, and calcium levels by adding Cal-Hypo to the skimmer in an attempt to create more iron precipitate to get caught in the filter, but it's an iffy procedure.

Metal sequestrants can bind to ferric ion, but they bind much better to ferrous ion which is why the usual procedure is to use a reducing agent such as ascorbic acid to remove metal stains and convert ferric ion to ferrous ion. Then one adds a metal sequestrant which binds to the ferrous ion keeping it dissolved in water and preventing it from getting oxidized back to ferric ion. One needs to add more metal sequestrant over time since chlorine slowly degrades it. As for copper, it's mostly in a single state so there isn't the same need for using a reducing agent. The removal of copper stains happens more from the use of acid though such stains tend to be difficult to remove because they penetrate more deeply than iron stains.

*Technically, it is the ion complex [Fe(H₂O)₅(OH)]²⁺ that produces the yellow color (in some over-saturated high concentrations it may be yellow-brown). This complex is formed in water due to the high charge density of ferric ion (similar to how aluminum forms complexes and floc -- in fact ferric ion is often used as a coagulant just like aluminum).