Likely calcium deposits

[257WbyMag]

See the attached photo for reference.

Note the white deposits on the tile and on the mortar between the individual rocks on the waterfall coping. This is the only place on the pool that has such a problem. Anywhere the water splashes from the waterfall apparently has this white and scaly buildup. I think that it is due to the previous owners (and their pool service's) lack of pH control coupled with a high CH. Although the CH is still 425 ppm, it is lower than what it was (>600 ppm) when I first bought the house and took over the pool.

To correct, I was thinking of maybe painting the areas with a dilute mixture of HCl... say 10:1 of the 31.45%, brushing, and then rinsing. Before I did something like this though, I wanted to pose the idea to the forum. I am doing BBB.

Current numbers are:

water temp: 69 degrees F
ambient temp: 70 degrees F
FC: 6.6 ppm
CC: 0 ppm
TC: 6.6 ppm
pH: 7.4
TA: 80 ppm
CYA: 55 ppm
CH: 425 ppm
Miller Lite: 3

Thanks!

Craig

 

[Butterfly]

I have no idea about the white deposits, but your pool and flowers are beautiful


btw, like your sig

 

[257WbyMag]

Thanks Joyce! I appreciate that. BTW, did you see my reply on your carpenter bee post? That's the way to get rid of them.

No problem on not knowing what the deposits are on my pool. I'm thinking that chemgeek will come by any time now and shed a little light on the issue.

Craig

 

[chem geek]

Craig,

Your current numbers have a saturation index of -0.4 (assuming 3200 ppm TDS due to the salt for your inline chlorinator) so would not normally show any signs of scaling. If the previous owner had the CH build up to 700 and the pH to 8.0, then that would be an index of +0.4 which might show some scale drying on splash-out, but it's not really when scaling normally occurs.

I'm guessing that this is more likely to be efflorescence caused by water seeping through the backside of the stone as it seems to be more prevalent at the possibly more porous grout. The water dissolves some material as it goes through and it crystallizes on the surface like a residue. Of course, you can first clean the stone/grout with a very dilute acidic solution and see if it comes back. If it doesn't, then your guess about it being the previously bad water chemistry was probably right. If it does come back, then if you can turn off the waterfall and clean it again then you can see what happens. That should tell you if it's from the waterfall or not.

Your water should be salty since you are using an inline chlorinator so it could just be salt buildup, but if you splash and rub it and let it dry (turning off the waterfall), then if it comes back white when dry it's probably not regular salt but more robust scale (i.e. calcium carbonate rather than sodium chloride).

If its efflorescence from moisture seepage (you've got watered plants very close by), then I'm not sure what you can do about that other than having a better moisture barrier on the other side of the stone.

Richard

 

[Butterfly]

Thanks Joyce! I appreciate that. BTW, did you see my reply on your carpenter bee post? That's the way to get rid of them.

No problem on not knowing what the deposits are on my pool. I'm thinking that chemgeek will come by any time now and shed a little light on the issue.

Craig

Craig, I'm going to the Beez post now. I was waiting to give a 'report' on the honey jar game

 

[257WbyMag]

Richard,

This isn't a salt pool. It's a chlorinated freshwater pool and that inline chlorinator is nothing more than a container with a valve to control water flow over some trichlor pucks. I haven't used it and instead, I've been doing BBB. With Jason's Pool Calculator, my CSI is showing to be -0.19 with those numbers. Some might say my FC is a little on the high side but I have been running it that way to account for the increased CYA. That was another issue when I took over this pool is that the previous owners had over stabilized pool water with a CYA of near 100.

I apologize for the confusion and I am going to take that "inline chlorinator" out of my signature line and I think it is confusing some folks to into thinking that I run a SWG. Also, for the record, when I turn the waterfall of, the white deposits remain in place.

Thanks Richard.

Craig

 

[JasonLion]

I believe that chem geek was asking if you clean up the existing white stains and then turn the waterfall off for several weeks do the stains come back, or do they only come back when the waterfall is running. That isn't the simplest experiment to perform but it would tell us quite a bit about how to fix it permanently.

I think it is probably efflorescence related to water getting behind the tile because of slashes from the waterfall. But that is just a guess.

Cleanup is most likely going to be dilute muriatic acid. Test a small area, you should see bubbling when you apply the acid. If it doesn't bubble or foam up then the acid isn't going to work. The acid won't hurt the tile at all but it could cause very minor damage to the grout if you use too much so be a little more careful around the grout lines.

The problem is that it will likely reoccur. If it is efflorescence then you need to seal the area behind that part of the pool wall so water can't get behind the tile. If it is directly from the waterfall then it is trickier.

 

[257WbyMag]

Jason,

That's kinda what I was thinking insofar as applying dilute HCl. I was thinking about a 10:1 solution of water to 31.45% HCl unless you suggest differently.

Craig

 

[chem geek]

This isn't a salt pool. It's a chlorinated freshwater pool and that inline chlorinator

Yup, the "inline chlorinator" confused me -- I keep forgetting about Trichlor inline chlorinators. With the pool not being an SWG, the saturation indices are 0.2 higher than I earlier quoted, so now at a very decent -0.2 as you say. The previous owner numbers could have had a saturation index (with CH 700 and pH 8.0) approaching +0.6 so possibly over time that could have led to scaling. Anyway, the cleaning with dilute acid and seeing under what conditions the white returns will help determine how to resolve this.

I don't know how dilute the acid should be for cleaning. Hopefully Jason or someone else knows. You aren't supposed to use acid on polished stones (e.g. marble, travertine, sandstone), but your stone does not look polished. Some web sites (e.g. this one) refer to using weaker acids than Muriatic Acid for cleaning. You'd have to really dilute Muriatic Acid a lot to make it weak -- about a 1000:1 to get to a pH of 2. A 768:1 dilution is one teaspoon in a gallon which is also roughly one drop in one cup.

Richard

 

[257WbyMag]

Thank you Richard. Nope, the stones are not polished. I will investigate dilution ratios, apply whatever I come up with, and see what happens. I will post results on this thread.

Craig

 

[duraleigh]

257,

If you've not used acid on calcium before, it will "foam up" when it is "cutting" the Ca.

Cleaning it off a porcelain appliance, 5:1 seemed to work. Test your 10:1 mix in a very inconspicuous spot first and then strengthen until it "foams".

 

[257WbyMag]

I think that I will try it on the tile since tile is the toughest when it comes to withstanding low pH exposures. If it foams, then I'll know it is calcium. If not, then it is probably something else altogether.