Why is my pool green after filling with fresh water?

PSC Ep. 89: Why is my pool green after filling with fresh water?

In today’s episode of Poolside Chat, Rob and Matt tackle another common swimming pool question: 
I just filled my pool and the water’s green. Why did this happen?

Most people are going to assume that it’s algae, but if it’s brand new water, that’s probably not the cause. It’s more likely that you have a lot of metals in the water, copper or iron. Your first instinct when you fill your pool with new water, is to shock it. But that shock then oxidizes the metals, that chemical reaction then causes the green hue in your water. This is common with refills that used well water or even water that hasn’t been shocked but instead contains a high level of metals.  

What can you do about it?

If you’ve already filled the pool and the water is turning colors, your first step should be to add a metal sequestrant like a Metal Control. Sequestrants do not purge the water of the metals but instead suspend it, prevent it from causing stains or unwanted effects. If you want to purge your water of metals, you’ll need a metal remover like CuLator. The CuLator metal remover is available in cartridges that can be inserted in your pump or skimmer basket

If you haven’t filled the water up yet, treat the water as you’re filling it with Metal Control. We’ve seen some cases too where people will shock it and they’ll add a metal– not a metal control, but an algaecide with a lot of copper. The copper in that algaecide can react with the shock and cause a green pool too so that could be a reason.

If you are planning to fill your pool with well water, a simple bobby hose extension can filter out metals as you fill the pool; this can elimnate or atleast reduce the need for further metal treatments.

If you have any other ways of filtering metals or suspending metals in your pool water, please leave a comment down below. For all your pool and spa needs, please visit us over at INYOPools.com


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4 thoughts on “PSC Ep. 89: Why is my pool green after filling with fresh water?

  1. What do we do if we have already added an algae ode to the pool? What do we do now to get rid of the green in a newly filled pool?

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