Bright Blue Stains on Pebblecrete Surface

[jayveebee61]

Hi there,

We recently bought our house and with it came an inground concrete pool, with the standard 'salt and pepper' pebblecrete surface. We are guessing the pool is around 16 years old at least.

Our issue is that along the pebblecrete surface of the pool, above and below the waterline - and mainly on the walls - are these bright blue stains. I have attached 3 photos.

I have had the rep from LoChlor out a few time times to look at the pool and we have tried LoChlor "MultiStain" Remover, Lo Chlor "CU Later" copper remover, and ascorbic acid and nothing has budged the stain - even a little. We used these products exactly as directed.

I have also applied a little pool acid (HCl) to one of the stains above the waterline, and scrubbing it with a nylon brush and it actually made the stain worse, resulting in a deeper blue colour.

I asked the previous owner - an old woman - if she knew what caused it and she did not know.

Just thought I would get in touch with you guys to see if you had any suggestions. At first because the staining was blue I though it may have been copper but the "CU Later" did not budge it at all. Also the colour is bright blue - not the blue-green hue of a typical copper stain.

The pool is saltwater chlorinated. At the moment the pool has zero chlorine/salt and pH is neutral as this was what was required to trial all the above products.

Any advice - very greatly appreciated.

[Teapot]

Now you have tried reducing the stain with acid which would then indicate metals being present. Try a chlorine tablet held directly on the stain for a bit and report back.

[jayveebee61]

Hi Teapot, my apologies for the delayed reply - have been away on holidays. Thank you for the suggestion re the chlorine tablet. Unfortunately this also has not worked on the stain. It's a real head-scratcher, this one!

[MRoach]

Hi

I have the same issue with my pool, did you ever figure out how to remove the blue stain?

Thanks