Save money! Using Calcium Hypochlorite Without Raising Calcium Levels

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kluke409

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Jul 20, 2015
1
Spring Branch, TX
Hey guys, I've never posted here, but figured I would share what I've done for years as a way of adding chlorine cheaply...and without adding calcium -

Basically:

  • I mix X-amount of desired calcium hypochlorite in a 5 gallon bucket (with water, almost to top), then secure with lid and put in shaded area.
  • Let sit for 24hrs.
    • Calcium & chlorine essentially separate into white chalky liquid on the bottom and liquid chlorine on top
  • The next evening, I siphon off the top portion (90%+ of top liquid) into another bucket and pour into deep end of pool.
    • IMPORTANT! Do not move the bucket at all once separated as it will re-mix depending on how much you move it.
    • (the siphoned liquid is a fairly clear, almost completely yellow, highly concentrated liquid chlorine)
  • Discard the leftover calcium at the bottom of the original bucket on whatever neighbors' plants you do not like
    • kidding
    • or maybe I'm not :crazy:

I have cost compared using various chlorinating methods and this seems to be the most cost effective way of chlorinating my pool. It takes a little time, but if you're frugal like me...it's worth the extra time.
 
I would be willing to try. Thanks! Using bleach STILL has me chasing a rising pH. Thus muriatic acid costs. Then, baking soda cost. Maybe liquid chlorine use would not raise the pH the way OTC bleach does. I've read all those posts that bleach really doesn't raise pH. I beg to differ.
 
quincy915 said:
I've read all those posts that bleach really doesn't raise pH. I beg to differ.
Click to expand...

For people using pucks or dichlor the switch to bleach seems like the bleach causes the pH to raise. But what's really happening is that the pucks and dichlor are acidic and they reduce pH so that the normal pH change of the pool is not as noticeable. In other words, the bleach is not raising the pH, the previous method of chlorinating was reducing pH.
 
quincy915 said:
I would be willing to try. Thanks! Using bleach STILL has me chasing a rising pH. Thus muriatic acid costs. Then, baking soda cost. Maybe liquid chlorine use would not raise the pH the way OTC bleach does. I've read all those posts that bleach really doesn't raise pH. I beg to differ.
Click to expand...

Bleach does temporarily raise pH when first added but as the hypochlorite is consumed, the pH comes down again to the level it was at when the bleach was added. Bleach addition is a pH neutral process over the life of the bleach. Liquid chlorine is bleach. They are the same. One is labeled and sold as liquid chlorine or liquid shock but the only difference is the hypochlorite concentration. Exact same chemicals.

You're saying you're fighting pH rise with muriatic acid then adding baking soda. What pH range are you maintaining? Why are you raising TA with baking soda? What TA levels are you seeing and targeting when you add baking soda?
 
Last edited:
quincy915 said:
I would be willing to try. Thanks! Using bleach STILL has me chasing a rising pH. Thus muriatic acid costs. Then, baking soda cost. Maybe liquid chlorine use would not raise the pH the way OTC bleach does. I've read all those posts that bleach really doesn't raise pH. I beg to differ.
Click to expand...

You say you use baking soda, but that means you probably have your TA set too high and that is the source of rising pH in the pool due to carbon dioxide outgassing. Pools are intentionally over-carbonated, but if you have too high a TA and too low a pH target, then the outgassing is faster and the pH rises. The pH would rise in your pool even if you were to use no chlorine at all. The pH rise from bleach is negligible unless you are using a poor-quality bleach with a lot of excess lye in it.

According to this post your TA is at 70 ppm so that's not terribly high, but you should not add baking soda to raise it any higher from there. Do you have aeration sources such as a waterfall, spillover, fountain, etc.? Also, what is the age of your plaster (i.e. is it relatively new)?
 
what is the actual FC concentration of the liquid you are adding? and what is that volume? If you are trying to maintain a proper daily level of FC you'd have to have a pretty good handle on those numbers.

I'd also think that super concentrated liquid chlorine is not safe to just dump in the pool without exposing liners or other components to too-high CH levels. And since it's a high concentrate, are you adding this every day, or doing enough to raise your FC to a level which will slowly come back down to your target over the next couple days? I'm curious to get the numbers behind it all.

Plus, since you're doing this outside, that high concentration CH is going to degrade quickly once it's dissolved from the Calcium. Even 24 hours might be enough to reduce it quite a bit.

kluke409 said:
Hey guys, I've never posted here, but figured I would share what I've done for years as a way of adding chlorine cheaply...and without adding calcium -

Basically:

  • I mix X-amount of desired calcium hypochlorite in a 5 gallon bucket (with water, almost to top), then secure with lid and put in shaded area.
  • Let sit for 24hrs.
    • Calcium & chlorine essentially separate into white chalky liquid on the bottom and liquid chlorine on top
  • The next evening, I siphon off the top portion (90%+ of top liquid) into another bucket and pour into deep end of pool.
    • IMPORTANT! Do not move the bucket at all once separated as it will re-mix depending on how much you move it.
    • (the siphoned liquid is a fairly clear, almost completely yellow, highly concentrated liquid chlorine)
  • Discard the leftover calcium at the bottom of the original bucket on whatever neighbors' plants you do not like
    • kidding
    • or maybe I'm not :crazy:

I have cost compared using various chlorinating methods and this seems to be the most cost effective way of chlorinating my pool. It takes a little time, but if you're frugal like me...it's worth the extra time.
Click to expand...
 
kluke409 said:
Hey guys, I've never posted here, but figured I would share what I've done for years as a way of adding chlorine cheaply...and without adding calcium -

Basically:

  • I mix X-amount of desired calcium hypochlorite in a 5 gallon bucket (with water, almost to top), then secure with lid and put in shaded area.
  • Let sit for 24hrs.
    • Calcium & chlorine essentially separate into white chalky liquid on the bottom and liquid chlorine on top
  • The next evening, I siphon off the top portion (90%+ of top liquid) into another bucket and pour into deep end of pool.
    • IMPORTANT! Do not move the bucket at all once separated as it will re-mix depending on how much you move it.
    • (the siphoned liquid is a fairly clear, almost completely yellow, highly concentrated liquid chlorine)
  • Discard the leftover calcium at the bottom of the original bucket on whatever neighbors' plants you do not like
    • kidding
    • or maybe I'm not :crazy:

I have cost compared using various chlorinating methods and this seems to be the most cost effective way of chlorinating my pool. It takes a little time, but if you're frugal like me...it's worth the extra time.
Click to expand...

The solubility of calcium hypochlorite in distilled water is 214 grams/liter (see this link). So in a 5 gallon bucket you could only dissolve 4.05 kg or 8.9 pounds of Cal-Hypo. So how much Cal-Hypo are you adding to your 5 gallon bucket? If more (accounting for % Cal-Hypo in the product), then the excess will precipitate as calcium hypochlorite so you would be leaving chlorine back.

Calcium hydroxide has limited solubility of 1.59 grams/liter (see this link) or a solubility product of 5.02x10-6 (see this link). A saturated solution of calcium hypochlorite would have a pH of around 11.7 so could settle out some calcium hydroxide. The saturated calcium hypochlorite solution has roughly 1M so this implies a maximum hydroxide concentration of sqrt(5.02x10-6/1) = 0.002 M or a pH of 11.4. So this is a very small amount of calcium removal.

To get more calcium to precipitate, one would need to add either sodium hydroxide (lye) to precipitate more calcium hydroxide or sodium carbonate (washing soda) to precipitate out calcium carbonate. This would in effect substitute calcium for sodium but at extra cost for these additional chemicals.

The separation of the calcium and chlorine doesn't make sense without adding something additional to, for example, precipitate calcium carbonate. If you were to use tap water then you would likely precipitate out some calcium carbonate and therefore remove some calcium that way, but if your tap water only had 80 ppm TA then the amount of calcium carbonate precipitated in 5 gallons would be only 1.5 grams of calcium carbonate. Now if you were to add sodium carbonate to this mixture, you could precipitate out the calcium as calcium carbonate and have sodium hypochlorite left in solution at around 13.8% Trade.

However, without the addition of carbonate or hydroxide (or something to precipitate calcium), I don't see how the calcium can "separate". Calcium is a positive ion so for it to separate into its own layer even if it didn't precipitate it would need negative ions to go along with it and there aren't any in significant quantity other than hypochlorite.

Of course, anyone here on this forum can simply try adding Cal-Hypo to a bucket of water below the level of saturation (i.e. below 1.8 pounds calcium hypochlorite per gallon factoring in concentration of Cal-Hypo) and see what settles after 24 hours and then take the water above what settles, add it to some larger volume of water, and measure any CH increase compared to the FC increase to see if enough calcium was really removed to make this practical.
 
Assuming complete transfer of chlorine from the calcium to the water a 1 lb bag will raise the FC in 10,000 gallons by 7.7 ppm. A gallon of 10% chlorine will raise the FC by 10 ppm. In my area a bag of 68% cal-hypo costs at least $2.50 and a gallon of 10% Na-hypo costs $3.00. That makes 32 cents / 1 ppm / 10,000 gallons for cal-hypo and 30 cents per 10%. Can't speak for Texas prices but here it would literally cost more for the hassle of doing this.
 

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