Large Amounts Of Calcium On Pool Walls

by Sandee
(Houston, TX)

We have a two month old salt water pool with beadcrete plaster. About 3 weeks ago we noticed a buildup on the polaris that looked like sand particles. Then the polaris bag started filling up with a white sand material daily.

We heated the spa and after getting it was unbearable. The plaster was so rough it would cut your skin. We could brush piles of sand from the walls.

We had a pool company doing the chemicals, so we checked the levels and the PH was above 8.2, the CL was above 3.0, and the alkalinity was very high. The pool company had been adding acid weekly but was not bringing it down. We added acid and it would come down for a day or two and then go back up.

We live in Houston, TX and nobody else is having an issue. We got a few cold nights but nothing else has been different.

How do we get rid of the calcium buildup and get our plaster feeling normal again. Pool company is stumped and everybody we bring out just keeps saying to add acid.

Nothing seems to be working and we can't even use our brand new pool. HELP!

Thanks for the question Sandee

My first question is did you recently have the pool replastered? The question says "we can't even use our brand new pool" so can I assume it is a freshly plastered pool? If it is a new pool with fresh plaster, you can expect some settling of the new plaster and some will come off. Many times this can happen if the pool was filled too quickly and the plaster didn't have a chance to cure completely.

2nd, I'd like to have your calcium readings. "High" is relative and means different things to different people. The alkalinity reading would help as well. For a salt pool you don't want to have the calcium any higher than 250ppm. The best range is between 150 - 250ppm. When I had my pool route in Arizona the fill water calcium level was very high, sometimes around 400ppm. I would need to drain and refill some pools every other year to keep it down.

pH doesn't increase without outside influences either. This can be through granular chlorine (which has a pH
level of 12), high pH fill water, or splashing around with causes the carbon dioxide (CO2) to burn off, thus increasing the pH.

How big is your pool and how much acid was being used? This is important because 1/4 gallon of acid in a 5,000 gallon pool is much different than 1/4 of acid in a 50,000 gallon pool.

I'd encourage you to test your fill water. Calcium hardness can't increase without an outside influence, mainly either calcium chloride, high fill water hardness, or the use of granular chlorine.

When the question says acid was added to the pool but "it" didn't come down, which one were you trying to reduce, the pH or alkalinity? Acid is used to reduce both the pH and total alkalinity but it depends on how to add it.

The high pH level and the high alkalinity level can contribute to plaster erosion. But again, I'll need the alkalinity reading to be sure.

Adding more acid to the pool a misguided hope that will clear it up, without a good plan and understanding of what is causing the readings to be off is completely wrong. You're wasting your time and money.

So, it could be simply the pH and alkalinity need to be adjusted, which is a simple process. I wouldn't worry about the chlorine being 3.0 or near that. I keep the YMCA pool between 3.5 - 4.5ppm and it's fine.

If the calcium is higher than 300ppm, you'll need to reduce it. The only way is to drain 1/3 - 1/2 of the water, refill, and balance out the chemicals. Get me the the alkalinity and calcium reading, the size of your pool, and how much acid is being used.

Do you have a sand filter and if so, is it shooting back back into the pool? And when you sweep the sides and bottom of the pool does plaster come up? It sounds like it could be a simple fix but I would need just a bit more information.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Calcium Hardness" category.

Swimming Pool Questions & Answers

Check back to this post for updates or answers.

Hope this helps and have a great Summer.


Comments for Large Amounts Of Calcium On Pool Walls

Average Rating starstarstarstarstar

Click here to add your own comments

Jan 18, 2015
Bead Crete Pool Plaster Finish
by: Sadee

It is a brand new pool that was filled mid-October and is 16,000 gallon pool. The plaster is beadcrete. The last test we did after adding 1/2 gallon of acid was FAC 3.0, PH 8.0, TA 130, CYA 50, Calcium Hardness 260, Salt 3000, phosphates 100. The pool company said those were good and try to keep them at that level by adding 1/4 to 1/2 gallon of acid when we see it rise.

The plaster does not seem to be coming off we even scraped it to see after draining down the spa. It is more of a sand type particals that sticks to everything - walls, floor, lights, jets, and polaris. The polaris bag fills with this white sand substance daily. Brushing and vacume help but still seems to be stuck to walls and seats making beadcrete feel like the worst sandpaper. Controlling the PH and TA slows the growth but not getting rid of what is already there. It took very hot water and soap scum remover to get it off the polaris which was completely coated.

I also wanted to add that the test on saturation index scale by pool company when it was first happening was at 1.2 Si. We also have an auto fill on the pool and chlorinator which is set at 5%. The tap water was tested for PH and was higher than 8.2 but not tested for Calcium. We have 3 other salt pools around us and none are having this issue.

Thanks for the follow up Sandee

Let's start with the chemical readings. The pH and alkalinity aren't too far off. Just small adjustments with acid will bring them down.

Be sure to have the pump running when decreasing the pH and pump off when decreasing the alkalinity. The links above go into greater detail. Wait for one full turnover of the water, about 8 hours, before retesting or making another adjustment. This is when you'll need patience.

The CYA, hardness, salt and phosphates are good. Here's some goods links about phosphates:

Looking over your comment I would rule out any chemical problems that could contribute to the sandy feeling. My next guess would be the application of the beadcrete.

Your issue could one or a combination of chemical readings that are inconsistent (which I can rule out from the what you gave), bad application of the beadcrete, or sand from the filter entering the pool, if you have a sand filter.

Beadcrete started to come into the mainstream of pools in the early 2000's and really hit its stride around 2005. This is when I ended my pool route in Arizona and moved to Oregon. I took care of dozens of pebble tec pools, but none with beadcrete finishes.

I've heard of these issue before concerning beadcrete. It seems that getting an even coat and application is difficult and some of the aggregate will eventually come off.

From my limited exposure with beadcrete, but all that I know about pools, the above information is the best I can do at this time. I've searched other areas concerning this issue. There seems to be limited information at this time but I'll keep researching and contact you if I find anything new.

Best of luck with your pool


Mar 08, 2017
Best plaster for salt water?
by: Jo T

We are preparing to re plaster our salt water pool - is there one type of plaster better than others? Our pool guy suggested wet edge peddle plaster. Any suggestions?

Hi Jo. Nowadays, you have a wide variety from which to choose. More than when I had my pool route, as new technology comes into play, and what customers demand.

The bottom line is this: It comes down to your personal preference and how much you are willing to pay. I'm not familiar with your financial situation, so I can only give general answers. With the name provided, you can research some more.

The plaster is only as good as the prepped surface, and those doing the job. I've seen new plaster jobs that peel within a couple of months. I've also seen plaster pools last 15 - 20 years, both salt and regular chlorine pools.

Pebble tec is a good choice as it can last up to 25 - 30 years with proper maintenance. I've taken care of several of them and they're wonderful. However, some people say it's a bit rough on their feet.

PebbleSheen and PebbleFina are a bit smoother than normal Pebble Tec and can have the same texture as regular plaster.

Aggregate pools are a new type of plaster pool. It's white or colored plaster mixed with other materials such as quartz, granite, river stones, or glass beads. You can find Aggregate finishes in either exposed or polished.

Now for the wet edge finish. I'd narrow it down to 3 kinds: Prism Matrix, Satin Matrix, and Primera Stone.

Satin matrix uses smaller stone and costs little more.

Primera stone is a polished pebble finish.

I actually like colored glass beads as they tend to not be as rough as normal stones, but "rough" is subjective. Again, it's all a personal preference.

Hope this points you in the right direction.


Click here to add your own comments

Return to Calcium Hardness.