What's This Deposit On My Pool Mosaics?

Any thing to do with swimming pools, fish ponds, or other man made structures which hold water (but not wells for drinking water).

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What's This Deposit On My Pool Mosaics?

Postby Greenside » Mon Dec 05, 2016 8:25 pm

You can see some details about our pool in the Your Building Story thread "Building a House in Chiang Mai At The Worst Possible Time", but here's the layout:

Simplified Pool Plan.jpg
Simplified Pool Plan.jpg (32.17 KiB) Viewed 274 times

We have a Asralpool VX Chorinator with a dual speed pump and a filter full of Zellbrite. The spa overflows into the pool and due to a poor bit of design the water doesn't fall from the lip of the spa but mostly runs down over the glass mosaics. After three years I have drained the pool to give it a thorough cleaning, since although he water is perfectly clear we do have trouble keeping green algae from growing on the steps and in the corners where the circulation isn't so good. What I find are white deposits that I always assumed was salt have formed below the water line on the mosaics and there is a white film over the part above the water line. Pictures below

The mosaics above the waterline have lost their colour due to a film of something although it's possible that exposure to the sun may play a part.



This doesn't taste like salt and I'm wondering what it is and how best to remove it. Scraping works on the lumps but doesn't shift the film so I'm hoping there is a chemical solution. By the way the unsightly brown stain on the spa is from using water from our borehole which had too much iron in it. Hydrochoric acid will remove it and now that we use city water I don't expect it to be a problem.
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Re: What's This Deposit On My Pool Mosaics?

Postby Klondyke » Wed Jan 18, 2017 10:38 pm

Obviously, it is the iron and/or alkaline residue. Even the town water will cause it, more or less. Surely, the HCL acid will help. Suitable safety caution when used and a reasonable concentration (acid into water, never opposite) is highly recommended.
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Re: What's This Deposit On My Pool Mosaics?

Postby Jentaiya » Tue Aug 15, 2017 11:16 am

Having a solid knowledge of this web site helped me a lot.
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Re: What's This Deposit On My Pool Mosaics?

Postby jazzman » Sat Sep 16, 2017 3:50 pm

That deposit is lime scale (calcium). Check your pH, total alkalinity, and water hardness.
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