removing calcium, options

tstex

Silver Supporter
Aug 28, 2012
1,788
Houston, TX
Hello to all,

I noticed when I ran the spa and blower [no heater on] to circulate water in lines, the blower pushes water over the spillover into pool. The net result is about a 1" to 1.5" water loss below the normal waterline. It was at this time that I saw a distinct calcium or water line around the spa on the 6" travertine sq's.

I am seeking options on what I can do to remove these? Would a bristle-brush w can CLR [Cal Lime Rust*] remover work? Is there an issue if during this process, the resultant material removed, CLR, etc goes into the spa? The only other option would be to have someone hold a towel under the area I scrub. * If this contains and acid-base, then it could possibly damage the travertine stone. I cannot use M-acid due to the harshness of the acid that would damage to etch the stone.

Notes:
I did apply the Dow StoneTech sealer to all of the travertine waterline tiles.

Our robotics shark cleans the pool tile water lines [travertine too], but periodically toss the shark [1 per 10 days] into the spa.


The waterline also changes in the pool during evaporation, but in the spa it always stays the same bc the spa spills over into pool and keeps the water line consistent.

Our pool was plastered/pebble-sheened in Jan-Feb 2015.

CH = 375-400

Thank you and pls let me know if you have any questions - txtex
 

ozdiver

LifeTime Supporter
Oct 17, 2014
585
Spring, TX
Rather than use CLR, you can dilute your MA to a more friendly concentration.
I have the same challenge with travertine waterline tile.
The calcium and travertine are both attacked by the acid.
There are abrasive blocks that you can manually remove the calcium but their use depends on you not having shiny travertine. Resealing would be necessary.

You could drop your CH a little to lessen the buildup, I run mine @ CH 275.
Not having all your numbers makes it hard to validate, but as long as you watch your CSI you are doing all you can to prevent buildup.
 

tstex

Silver Supporter
Aug 28, 2012
1,788
Houston, TX
Thank you very much Oz - appreciate your follow-up.

My travertine is a non-shiny tumbled that is very porous. Any place that gets any form of acid, it etches pretty easily. I do have, however, some extra stone that I could try it.

I heard about 8oz of MA per gallon of water. That is 8/128 = .0625 or a little more than 6% strength. Is there a lesser concentration that will work?

You mention abrasive blocks..any specific make/model/brand?

I am going to reseal this time w Aqua Mix's EnRich N Seal...it's expensive but is really supposed to do the job.

My pool is 10 months old, so I am still prob leaching Ca. My CH was 375-400. Hopefully it will start going down as the leaching out process ceases.

Thanks again,
tstex
 

ozdiver

LifeTime Supporter
Oct 17, 2014
585
Spring, TX
The concentration is really to deal with our human deficiencies in reacting to the rate of oxidation.
The more diluted the slower the reaction.

I used Poolstone http://www.amazon.com/gp/product/B0033PRISQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00

It is recycled glass.
It wears very quickly but conforms to the surface quickly.
You will notice scuffing if you work it too hard.
I suggest using something to scrape the big chunks off prior to using this to clean it up.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,944
Tucson, AZ
One option is soda blasting. It typically requires getting a professional tile cleaner in to do the work. There's an outfit here in AZ that does kierserite blasting. Kierserite is a hydrated allotrope of magnesium sulfate. It's perfect for blasting of calcium scale but not damaging tile glazing. Not sure how well it work on travertine.

One could buy their own air compressor and bead hopper for a DIY setup, but the pros have the high end equipment.


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tstex

Silver Supporter
Aug 28, 2012
1,788
Houston, TX
Thanks to all. My inclination is to go the route of getting a very good scrub-brush/pumice/something that lasts awhile or something of this nature and apply w a lot of elbow-grease. My main problem is the calcium leaching from curing gunite combined w water for a 400 CA...this is mainly the spa where the robotic shark cannot work and scrub the walls like it does in the pool...I am going to drain the spa about 4-6" below bottom of travertine tile line, then go at it..rinse, what and apply the best sealer, wait 24 hrs then refill...thanks again
 

Ale_Brewer

Well-known member
Aug 7, 2015
225
Plano, TX
In my experience, the method Matt mentioned is the most effective for complete removal without damaging the pool surface. However, I have recently heard about a company here using tiny balls of dry ice as their media for this method and I am very interested in learning more. I suppose the biggest advantage is that there is no residual media left in the pool as the CO2 will just evaporate. I am curious how long that would take and what effect it would have on water chemistry, i.e. pH.


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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,944
Tucson, AZ
In my experience, the method Matt mentioned is the most effective for complete removal without damaging the pool surface. However, I have recently heard about a company here using tiny balls of dry ice as their media for this method and I am very interested in learning more. I suppose the biggest advantage is that there is no residual media left in the pool as the CO2 will just evaporate. I am curious how long that would take and what effect it would have on water chemistry, i.e. pH.


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That's pretty neat if it can work!! Let me know what you find out. I doubt the chemistry impact is very high as a tiny dry ice sphere would likely sublimate the minute it hits the water. At that point it's not likely to dissolve much.


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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,944
Tucson, AZ
I just checked and there's a company in Phoenix that does this but it looks like they want to establish business-to-business relationships, not a retail/consumer outfit. Still, some of the YouTube videos on it look promising...
 

tstex

Silver Supporter
Aug 28, 2012
1,788
Houston, TX
The CO2 is used as a propellent I believe but I'm wondering of the sustained cold temp of the CO2 help to freeze the Ca & once frozen, the continued onslaught of material breaks off the frozen or more fragile Ca? I'm just wondering what this process does to travertine, which is a very porous & carbonate/softer stone? Would it possibly chip the stone in the areas where the porosity is more honeycombed (on a much smaller level) that is less structurally stable? Little research here w this process. Thanks
 

Ale_Brewer

Well-known member
Aug 7, 2015
225
Plano, TX
tstex: dry ice is the solid form of CO2. They might use gaseous CO2 for the propellant to keep the dry ice from "melting" right away but most media blasting systems use compressed atmospheric air as the propellant. Typically with soda blasting you have HPLV (high pressure, low velocity) dispersion so I would think it would be safe for something even as fragile as travertine. I know it's used regularly on other kinds of very porous stone.

chem geek: That begs the question: How much dry ice media would be used in the process? The amount by weight may be significantly less because of the increased surface area/mass ratio of small beads. Therefore a significant drop in pH may not occur as opposed to a 60 lb. block


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chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
As I noted in my post in the dry ice thread, "Adding one pound of dry ice to 10,000 gallons would drop the pH from 7.5 to 7.0 if the TA is 100 and if all of the gas dissolved in water." When I added leftover dry ice in my pool, I registered a pH drop consistent with about half the amount I added so I presume the rest outgassed and did not dissolve in the water. So it does not take anywhere near 60 pounds to get a drop in pH.
 

Ale_Brewer

Well-known member
Aug 7, 2015
225
Plano, TX
From Wiki: "Dry-ice blasting involves propelling pellets at extremely high speeds. The actual dry-ice pellets are quite soft, and much less dense than other media used in blast-cleaning (i.e. sand or plastic pellets). Upon impact, the pellet sublimates almost immediately, transferring minimal kinetic energy to the surface on impact and producing minimal abrasion. The sublimation process absorbs a large volume of heat from the surface, producing shear stresses due to thermal shock.[2] This is assumed to improve cleaning as the top layer of dirt or contaminant is expected to transfer more heat than the underlying substrate and flake off more easily. The efficiency and effectiveness of this process depends on the thermal conductivity of the substrate and contaminant. The rapid change in state from solid to gas also causes microscopic shock waves, which are also thought to assist in removing the contaminant."

If the media sublimates immediately, the amount of CO2 that ends up in the water would be minimal or none. In theory, that would mean no change in pH. Very interesting...


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