Using Calcium Hypochlorite for sanitizer -- potential issues?

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J

jgold723

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Jul 5, 2016
41
Biddeford, Maine
Years of using the tri-chlor hockey pucks for sanitizer left me with a very high CYA (180+) and a recurring algae issue. Last year I abandoned the pucks and switched to liquid chlorine... without much difference. This year I'm trying calcium hypochlorite... partly because I can get it delivered -- I have to go out for the liquid chlorine. So far, so good -- I've been open for a month and the water is crystal clear. I add a pound of cal hypochlorite every two or three days and I test the water regularly. A pound moves the chlorine up to 10 - 11 ppm and then it fades to about 5 ppm after a couple of days. CYA is down to about 100.

I sprinkle the dry product along the edge of the pool when I apply it.

Are there any issues I should be aware of using this method? Would it be better to add the cal hypo directly to the skimmer while the filter is running to avoid potential bleaching issues with my liner?

I believe my signature has my pool specifics, but if not, it's a 20,000 gal inground with a vinyl liner in southern Maine.
 
The obvious thing to watch for is CH buildup. Every 10 FC you add is also adding 7 CH. Low CH is not a problem for vinyl but high CH can cause scale.

Don't pour anything down the skimmer.

I'd dissolve the powder in a bucket of pool water and then just add it like bleach to the return stream.
 
I was told it can also cause wrinkles in vinyl liner if you dump a lot in one area. As long as you dillute like Richard said, you should be fine.
 
jgold723 said:
Both very helpful, thank you. Richard, when you say add it to the return stream, I'm assuming you mean pour the solution in above the return jet? Why not add it to the skimmer? My calcium level here is pretty low, 180ppm at last test.
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Because it's standard practice to not add anything to the skimmer but DE. And that's only because there isn't any other way of getting it in the filter. People have clogged underground pipes with clumps of stabilizer, and others had the granules slip through the pump basket and make horrible grating noises in the impeller. Acids can etch metal components. Really high chlorine -- a strong oxidizer if you ever paused to read the package warnings -- could be rough on seals and O-rings. It is just plain good practice, like treating all electrical wires as hot even though you killed the circuit breaker. Once you start making a whole bunch of exceptions, it's no rule at all.
 
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CYA buffers the FC loss....it doesn't eliminate it. Two comments.........

You are losing too much FC for Maine and 100 CYA......you almost surely have algae in your pool consuming chlorine.

100 CYA is wa-a-ay too high....almost unmanageable.

My suggestion would be to replace about 1/2 of your water reducing the CYA to about 50 and ONLY THEN SLAMming the pool to get rid of the algae
 
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Last year I abandoned the pucks and switched to liquid chlorine... without much difference.
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Actually, there was a HUGE difference. You were no longer putting CYA in the water. Cal Hypo puts CH in your water you will likely have too much by the end of the summer. It has other issues that can cause cloudiness, etc.

liquid chlorine is the VERY BEST way to sanitize you pool......bar none. It is inconvenient but be aware of the tradeoffs when you use alternatives. You might consider an SWG but the front money is substantial.
 
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I think liquid chlorine method was about perfect for disinfecting my pool. Worked absolutely perfect for 5 years on my pool but I really did get tired of the jug-lugging and switched to salt. This is even better for us since my wife likes the "feel" of the water much better. Use of pucks or calcium containing compounds will eventually cause build ups and the only real way to fix this is to drain periodically. With a liner and low levels of CH to start calcium hypo may be a better compromise but now you're bucket lugging instead of jug lugging. If it were me I'd look at salt. It does cost up front but in the long run it's about the same cost or slightly better than liquid chlorine.

Chris
 
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Your CYA might actually be well over 100. The typical CYA test only reads up to 100. Anything higher than that will still read as 100. Try diluting your pool water sample 50/50 with tap water, rerun the CYA test, then multiple your results by two.

Either way, you really should drain a large portion of your water to get your CYA lower, down to 30 or 40.
 
Ah, that makes sense -- thanks. I've been advised of the water swap and it's on the list of possibilities. I've been hoping to avoid it because our water rates are high here. Last year my CYA was 180 so I switched to liquid chlorine. This year it's about the 100 I mentioned (I did do the dilution test, so I feel reasonably good about that number). I'm hoping I can keep bringing it down gradually with the usual water loss/replacement. So far things are manageable -- no green pool yet. But I do appreciate the advice.
 
jgold723 said:
Just out of curiosity, but what's the ballpark cost of switching to SWG?
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For your size pool you should go for a model that produces at least 1.5 lb chlorine per day. TFP recommends a system that is sized for twice the volume of your pool which equates to about this chlorine production. About $1100 for your size pool if you DIY. Cost of the chlorinator is ~$1000. Salt is cheap ~$50 for your pool is typical for your size pool using big box store salt. Add a few bucks for incidentals. If you pay to have it installed using same sizing criteria labor varies a lot depending on your equipment layout. Rough guess is $500-$1000.

Chris

PS responding to your questions is easier for our experts to get you timely response if you complete the equipment list in your signature. Brand and model numbers are greatly appreciated!
 
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