White stains on ceramic tile

[PoolFrog]

Hello,

I've attached a picture showing some white stains that we have on our blue ceramic tile around our spa spillover. We've only owned the house for a couple of months, so we have no idea how long these stains have been there. Our water is very high in CH because the previous owner's pool service used cal-hypo once a week to shock. Since we've owned the pool, we've put nothing in the water except bleach and some muriatic acid. What's odd is that these stains appear where the water doesn't make contact with the tile. Any ideas what these stains could be from, and how to remove them without affecting our nice clear water?

Thanks!

 

[ComputerGuyInNOLA]

It is probably calcium scaling. Pour a little muratic acid on it and see if it fizzles. If so it is calcium scale. You need to post a full set of test results so people can better help you. What test kit do you have?

 

[PoolFrog]

I have the TF-100. The last time I checked CH a couple of weeks ago, it was consistently reading 860. Since it was so consistent, I stopped checking it regularly in order to save reagent because nothing has been added to the pool that would have changed the reading.

My other numbers are as follows:
CYA 70
FC 8
CC 0
TA 100
pH 7.9 (need to add acid anyway to lower this)

Will the muriatic acid remove the stains, or will that just indicate if it's indeed calcium?

 

[JoyfulNoise]

It's most likely evaporite from mist/splash created by the spillway. Evaporite is as the name sounds, water evaporates and leaves behind all the solid compounds in it. It's mostly a mixture of calcium carbonate and salt. That being said, sometimes a little diluted Muriatic acid in a spray bottle (5:1 water to MA, always wear eye protection!) will work wonders.

If it becomes thick and adherent (you can't scrap it off with a finger nail) then you might consider a pool tile cleaning service and one that specializes in soda blasting (kieserite, aka magnesium sulfate, blasting). I had bad calcium scale all over my pool once and I needed a professional clean. The nice part about kieserite is that it is hard enough to blast away the calcium scale but soft enough not to damage the glaze on ceramic tiles. Unlike using a pumice stone, kieserite will not damage grout or tile glaze.


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[duraleigh]

Will the muriatic acid remove the stains, or will that just indicate if it's indeed calcium?

It'll usually remove it completely. Use with caution. The process will start over so you'll have to do it from time to time but yours does not look too bad and will likely clean up nicely.

 

[PoolFrog]

Ok, thanks for the suggestions!