Soda Ash to Lower Calcium?

[Dormdweller]

Going through the forums I see a lot of Questions regarding cool owners that have very high calcium levels and people who struggle to get the calcium in line. Theoretically chemistry wise, adding soda ash to the pool should raise the pH locally enough which makes the pool cloudy and traverse in a wave from the point of addition to the rest of the pool. This cloudiness should be the reaction of calcium with a carbonate ion from the soda ash forming calcium carbonate which is insoluble and would precipitate out of the pool to the bottom where can be vacuumed up or through the skimmer filter and flushed out. This should lower the calcium content. After calcium carbonate is formed and the pH can be adjusted back down using muriatic acid and if total alkalinity is too high can be adjusted in the same manner dump chemical in and this should lower the calcium content. After calcium carbonate is formed and removed, the pH can be adjusted back down using muriatic acid and if total alkalinity is too high can be adjusted in the same manner. Chemistry why’s it should leave 50 to 80 ppm of calcium if enough soda ash is added.

My Background: Chemical Engineer

Some References:

Water Softening - Sodium Carbonate - Soda Ash | Sodimate

Sodimate feed systems are widely used with sodium carbonate to remove hardness from water caused by calcium and magnesium minerals.

sodimate-inc.com

See attached pdf.

Does anyone experienced see any issues with this method?

 

[mknauss]

Welcome to the forum.
Sadly, it does not work that easily in a pool water environment.
See a recent thread - Calcium Removal from Pool Water to Address Water Line Scale
For more thorough discussion, let's call in @JoyfulNoise

 

[JoyfulNoise]

The amount of calcium removed would be minimal at best and cause lots of pH rise. Theoretically what you are describing is similar to a lime softening process. Theoretically, yes, it would work. Practically it would be nightmare as you can not control the scale formation. Uncontrolled calcium scaling can wreck a filter, a heater and an SWG. Put simply, it’s not worth the bother. Draining and refilling will always be the best, safest and least costly method.

 

[flynwill]

Farmers where I grew up would often fertilized their crops by injecting anhydrous ammonia into the irrigation water. The rise in PH would instantly induce a cloud of calcium precipitates out of the Colorado River water Resulting an a layer the better part of a foot thick in the bottom of the concrete irrigation ditch by the time the irrigation was complete. I always wondered if there might be a way to soften water this way. The problem, of course, is how to remove the ammonia once you have precipitated out the calcium.

 

[mgtfp]

Farmers where I grew up would often fertilized their crops by injecting anhydrous ammonia into the irrigation water. The rise in PH would instantly induce a cloud of calcium precipitates out of the Colorado River water Resulting an a layer the better part of a foot thick in the bottom of the concrete irrigation ditch by the time the irrigation was complete. I always wondered if there might be a way to soften water this way. The problem, of course, is how to remove the ammonia once you have precipitated out the calcium.

Two problems with this, and you are mentioning both in your post:

1)

ammonia

That is the last thing you want in your pool, ammonia creates an enormous chlorine demand:

Ammonia - Further Reading

www.troublefreepool.com

2)

Resulting an a layer the better part of a foot thick in the bottom of the concrete irrigation ditch by the time the irrigation was complete.

The reason why you want to remove calcium from pool water is because of the scaling problem it creates. This method induces this exact scaling problem. Yes, some of the scale will just fall out of solution as powder/flakes and can be vacuumed to waste. But some will also create layers of scale on surfaces in the pool, pipes, heater, filter and SWG.

 

[JoyfulNoise]

Most water treatment processes that soften input water from rivers and surface sources created huge amounts of mineral “sludge”. It’s a major problem that has to be handled early in the process by allowing for sedimentation and removal. Some of the sludge can be dried and sold as fertilizer but the vast majority of it winds up in landfills. It doesn’t have much use.

All that cloudiness was essentially the “mineral sludge” in your pool.

 

[JamesW]

Theoretically chemistry wise, adding soda ash to the pool should raise the pH locally enough which makes the pool cloudy and traverse in a wave from the point of addition to the rest of the pool.

For your pool, you could add about 22 lbs of Borax to raise the pH (increase borate by 50 ppm) or you could use 4 to 5 lbs of sodium hydroxide or you could use trisodium phosphate, which will create a lot of calcium phosphate.

Increasing the pH with sodium hydroxide first would increase the effectiveness of TSP.

All of the ideas are not recommended as the risks and side effects are all too high.

TSP would add a lot of phosphate, which you do not want.

You can remove phosphate with lanthanum, but this gets expensive and it’s not worth doing at that much phosphate.

Reverse osmosis is available in some areas.

Weekly Pool Service and Maintenance in Dallas | Weber Pools | Weber Pools

Weber Pools proudly offers pool service and maintenance as well as recycling swimming pool water to lower Calcium Hardness, TDS, CYA, and waterborne diseases in both residential and commercial pools.

weberpools.com

Reverse Osmosis for swimming pools in Dallas, Texas

Reverse Osmosis filtration is the best filtration to lower Calcium Hardness, TDS, and CYA in Dallas Texas

weberpools.com

In almost every case, dilution is the best option.