Calcium on flagstone?

[bdrums]

Pool was filled about 2 1/2 months ago. I've been managing the chemistry.

CL - 4
CC - 0 (sometimes 0.5)
PH - 7.5 (I let it rise to 7.8 then add acid to lower it to 7.5)
CYA - 30 (I'll raise it when it gets spring time)
TA - 80 (been 80 for a while. was a high of 100 right after PB balanced the water following fill)
CH - 325 (rock steady)

What do you think the white deposits are? They are ONLY on the spillway of the spa. Spa has been heated and used 4 or 5 times since fill.

I tried a 10:1 dilution of MA. Splashed it on with a cup and tried brushing with the pool brush on one spot. It got a little milky and some of it came off. Some of it appears pretty dang hard. Continued splashing with 10:1 dilution and brushing made no progress.

What should I try next?

Thanks.

 

[JoyfulNoise]

Likely efflorescence or evaporites or both. Water from behind the spillway infiltrates the flagstone which is like a sponge. The evaporation of the water from the surface of the flagstone drags water and minerals in from behind and leaves a deposit on the surface. The efflorescence and evaporite will be a mix of calcium, salts and silicates which can be very hard to remove. There are stone cleaners (Prosoco makes a variety of them) for cleaning efflorescence and mineral deposits. You can try that but if it fails to clean it all off, you may need to hire a professional cleaner to come in, one that preferably uses soda or glass bead blasting to remove the deposits.

Did you seal the flagstone surfaces of the spillway? If not, you should or else this will keep happening. DuPont makes several different kinds of stone sealers.

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It will also tend to happen on your FS coping as well, although to a lesser extent and more slowly than the spillway.

 

[duraleigh]

You should try a stronger solution.....10:1 will not touch it.

Typically, I have used 3:1 with no harm at all. Use common sense and observe your results.

 

[bdrums]

Likely efflorescence or evaporites or both. Water from behind the spillway infiltrates the flagstone which is like a sponge. The evaporation of the water from the surface of the flagstone drags water and minerals in from behind and leaves a deposit on the surface. The efflorescence and evaporite will be a mix of calcium, salts and silicates which can be very hard to remove. There are stone cleaners (Prosoco makes a variety of them) for cleaning efflorescence and mineral deposits. You can try that but if it fails to clean it all off, you may need to hire a professional cleaner to come in, one that preferably uses soda or glass bead blasting to remove the deposits.

Did you seal the flagstone surfaces of the spillway? If not, you should or else this will keep happening. DuPont makes several different kinds of stone sealers.

- - - Updated - - -

It will also tend to happen on your FS coping as well, although to a lesser extent and more slowly than the spillway.

Wow. Thanks for the explanation. Nothing is sealed. The PB did not indicate there would be any problem and we only talked sealing when I asked about a SWCG, which we didn't get. There has been some very light white stuff on some of the coping, but we dismissed it as something different. Now that I've read this, I can see that it is related.

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You should try a stronger solution.....10:1 will not touch it.

Typically, I have used 3:1 with no harm at all. Use common sense and observe your results.

Thanks. I was going very conservative just to see if it would do anything. Will try a stronger dilution and then look for a commercial product if that doesn't work.

 

[Swampwoman]

Bdrums, I am presently cleaning efflourescence off of an interior slate floor I just had installed so unfortunately have grown quite familiar with the process (This despite supplying the contractor with distilled water to avoid efflorescence from my well water....I'm guessing he did not use same for cleanup and then over washed my poly grout ;(

As such, I have two suggestions that might assist you. At Harbor Freight (and NOT lowes or hd) you can find a nylon cup brush that attaches to a drill. If the efflorescence is crystalline in nature, this will help your acid cleaning efforts in bad spots. After using acid (I'm running a 50/50 mix myself) be sure to rinse the stone with a neutralizer -- 1 cup baking soda for every 10 cups water. Rinse again with fresh water after neutralizing. These stes are necessary after acid cleaning to avoid etching and prep for sealing -- sealer won't work right if stone is acidic...you can test with litmus paper if you like.

Once you have it looking the way you want, be sure to use a sealer for porous stone...eg miracle 511 makes a specialty sealer for deep porous stone...or one called seal and enhance that will darken the color of the stone. (Test first to see if you like it.) neither of these give a wet look or anything -- natural finish.

Drytreat and Aldon are two other brands that make products for efflorescence and sealing same.

Nail it now and your beautiful build will stay nice a lot longer Hope the info helps.

 

[bdrums]

Thanks swampwoman.

We're waiting for our PebbleTec company to drain and re acid wash our Pebblesheen install. Then I'll figure out sealing. Still want to clean up what's there now.