Why Do We Have This Blue Powder In Our Salt Water Pool?

by Suzann

I have question about pool treatments.

Looking for an answer to my pool water issue.

We recently switched from an ionizer pool filter system to a salt/sand filter and pump system.

We are now having issues with a blue powder residue in the water and when water comes out of the vacuum it leaves this blue powder on the deck.

Our pH and alkalinity are very low - overall hardness is very high.

What can I do to properly treat my water and get it balanced for safe swimming!!??


Thanks for the question Suzann

Many times it could actually be the heater. Some heaters containing copper will leave a light blue residue or powder looking substance in some pools.

Does it brush off or is it the color of copper? Your question says the pH and alkalinity levels are low, so this could be the issue.

If the pH level is below 7.0ppm, you could be looking at copper stains in your pool.

I would recommend that you take your water in to be tested for metals. If you don't have a heater, your fill water might be high in iron and copper.

A metal sequastrant might be in order in you have a high metal count.

Because metal sequestrants break down over time and get filtered and backwashed out, you need to weekly dose your pool if you have high iron and copper.

Metal sequestrants that are based on HEDP, phosphonic acid
or something similar are the most effective.

Jack's Magic Blue, Purple, and Pink Pink Stuff, Metal Magic, Metal Free, & Metal Klear are very good.

Adjust your pH to 7.6 - 7.8ppm and alkalinity between 80 - 100ppm. You need to check the salinity level of your pool as well.

I've used a Myron Salt Meter for the last 3 years at the YMCA pool.

You can call TMI Salt Pure and purchase it. They're based in WA state.

Also ask for salinity water to calibrate your meter.

For the hardness, you want to keep it between 150 - 250ppm.

This is so the salt cell won't clog up and calcify. The only way to reduce water hardness is to drain 1/3 - 1/2 of the water and refill.

There are no chemicals to reduce hard water.

Calcium Hardness

Saltwater Systems For Swimming Pools..High Calcium & Iron..

Here are some good links to my alkalinity and pH pages. They will show you the best way to make these adjustments:

Swimming Pool pH Levels

Pool pH

Pool Alkalinity

Total Alkalinity

And the salt water pool pages:

Salt Water Swimming Pools

Chlorine Generator

There's also good information on the pool Q&A pages for salt pools and chlorine generators:

Swimming Pool Questions and Answers

Hope this helps and have a fun and safe swimming season.


Follow Up Comment:

By: Suzann
Date: June 8, 2011

This is fantastic information - thanks so much -

Great website too!

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Above Ground Salt Water Pool..Algae..

by gidget
(new iberia la)

I have an above ground salt water pool.

How do I get rid of the green algae in my pool from the winter time? What do I need to do?

Good question

Whether it's an above ground salt water pool or any pool for that matter, I know many people are going to have algae pool water come Spring, so here it goes. You can also find more in-depth info on these pages:

Remove Swimming Pool Algae..Swimming Pool Chemistry..Swimming Pool Care..

Green Pool Water..Swimming Pool Algae..Chemistry..Care

First you'll need to bring your water level to the correct level and be sure your filtration system is clean and running properly.

Next is to scoop out any and all debris from the pool. Scrub the water line to loosen up any debris on the walls and water line. Brush the walls, steps, and floor of the pool with a good brush. You can find this at any good pool supply store.

Then bring in line these chemical levels:

pH 7.2
Alkalinity 80 - 100
Calcium Hardness 150 - 250

Put chlorine tabs in the tab feeder or float. You want to get you cyanuric acid (CYA) level up.

Go here: Adjust Your Swimming Pool Chlorine..Swimming Pool Chemistry..Swimming Pool Care. to see the amount of chlorine and CYA you need for a good super-chlorination.

Another good page is: Pool Shock..How To Shock A Pool..Swimming Pool Chemistry..Care..

Be sure to brush throughout the shocking process to break up any residual algae. Backwash once per day and keep the water level correct.

The above pages will give you the perfect way to have a clean pool this Spring and Summer.

Thanks for your question

Best regards


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