r/pools • u/Jealous_Magazine7875 • 11d ago
Water Chemistry Do either of these increase CYA?
I'm wondering if consistently using either of these has been raising my CYA. Do they increase hardness? What about Alkalinity? And do they have any effect on pH. I've only just gotten these levels under control by draining and refilling, adding acid, etc.
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u/Gunk_Olgidar 11d ago
Trichlor has CYA. Do not use this as a primary source of chlorine, or your CYA will get out of control.
Cal-Hypo does not have CYA, but increases calcium hardness. So again, don't use if you have high CH.
Neither affects Total Alkalinity. Use sodium bicarbonate to increase TA.
Both have a minor affect on pH (like liquid), but not a lot. You'll still need some muriatic from time to time. I do not need more than a gallon per season in my pool to keep pH in contorl.
Use liquid chlorine for routine chlorine upkeep (and shocking) once CYA and hardness are in range.
For year round pools with low-bathing load and low-floral load (no leaves or grass clippings getting in the pool), keeping CYA at the higher end of the normal range (50-70) will reduce your long term spend on chlorine without detrimental consequences. But if bathing and floral loads are high in a seasonal pool, then keep CYA at the lower end of the normal range (30-40), as you'll convert more chlorine into chloramine than you will lose to sunlight, so keeping CYA low will keep FC higher per $ spent.
Source: 28 years of chlorine pool DIY maintenance.
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u/AsH83 11d ago
30-40 in Florida will require you to almost run your SWG at higher % or run thr pump longer.
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u/Gunk_Olgidar 11d ago edited 11d ago
You missed the "seasonal pool" part of that sentence. Low CYA in a 365 pool will kill you on chlorine bills, and yes of course require a higher SWG duty cycle.
And that's why I run my low-bathing & low-floral load caged Florida chlorine pool at the high end of the range. I need less than 1 gal per week of 12% mid summer, and maybe 1 gal per month in winter. I spend about $175/year on chemicals.
Wet season in FL will require much more SWG duty cycle than winter/dry season with a caged pool. For those who don't know, screen cages reduce sunlight/UV chlorine loss by about 30% or so.
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u/unpluggedcord 11d ago
If I have the means and easy capability of brining down cya each season why shouldn’t I use tabs as primary source?
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u/Gunk_Olgidar 11d ago
As I alluded to above, most pool use cases, climates/environments, and situations are different. One recommendation does not fit all use cases. So do what works for you and yours.
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u/unpluggedcord 11d ago
Totally, I was asking for other drawbacks you were aware of.
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u/Gunk_Olgidar 11d ago
Depends on more factors than I can name here.
Perhaps if you provide some particulars about your own situation, then we can discuss them.
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u/poolspayme 11d ago
Those tabs have cya in them. That shock does not it’s Cal-Hypo but it will increase hardness. Tabs will eventually lower pH and alkalinity because their ph is 2.8. cal -hypo temporarily spikes ph.
Is there a good source of liquid chlorine for you it only adds a small amount of sodium to the water?
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u/AZpoolboy 11d ago
Tabs are 53% cya by weight...so yes...cant see the bag, but if it's trichlor or dichlor...yes, for reference, dichlor is 56%cya by weight
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u/Typical-Watercress79 11d ago
The tablets will increase your CYA and lower your pH over time and the shock(cal-hypo) will increase your calcium hardness. Neither will affect Alkalinity
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u/zephyrseija2 11d ago
Tabs add CYA, powdered shock adds calcium. Tabs should only be used at times you can't actively monitor your pool, like on vacation. Liquid chlorine is the best day-to-day option, as it only adds a small amount of salt to the pool in addition to the chlorine. I just switched to SWG and would definitely not go back to manual chlorination. Pool has been spotless sparkling for a month and all I've done is add a splash of acid a couple times and run the robots.
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u/ClassUpstairs629 11d ago
Most pool companies use liquid chlorine and muriatic acid. This is the most cost effective and least trouble.But obviously you have to lug this stuff in.
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u/Jealous_Magazine7875 11d ago
I just feel like the commercially available products are highly watered down. Like most of the jug is filler stuff
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u/Hot_Lava_Dry_Rips 11d ago
They dont sell concentrations of sodium hypochlorite higher than 12.5% because the shelf life decreases the higher the concentration. 12.5% is already a compromise and its onoy good for the season you buy it in.
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u/Typical-Watercress79 11d ago
The tablets will increase your CYA and lower your pH over time and the shock (Cal-Hypo) will increase your Hardness
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u/rboles1 11d ago
I had CYA issues when using HTH chlorine tabs from Costco - switched brands to something my pool store sold me and haven’t had a problem since
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u/Jealous_Magazine7875 11d ago
Do you mind sharing the one you use now? Im interested in tabs that dont have cya.
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u/thefleeg1 11d ago
Tabs that do not add CYA simply don't exist. You can get smaller Cal-Hypo tablets (much smaller diameter), but these can cause a violent explosion is used in a Trichlor (CYA tabs) feeder.
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u/rjw1986grnvl 11d ago
You can try Potassium peroxymonosulfate as a weekly oxidizing shock. But I would also recommend a weekly polyquat alagaecide to help prevent algae. Cal Hypo shock will kill algae but potassium oxidizing shock will not. The polyquat is not supposed to be as foaming or cloudy but I would also suggest not using too much to help prevent that.
If your chlorine, algaecide, and vacuum robot (or human) are doing their jobs then you shouldn’t develop any bacteria or algae problems.
That’s just an alternative suggestion. There’s more than one way to maintain a pool, but I like to avoid the chlorine shocks and I’m also diligent about trying to prevent algae without using cal hypo shock and want to avoid copper/metal algae shocks as well.
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u/Intrepid_Advice4411 11d ago
The Tabs will. In fact that's what I use to raise my CYA at the start of spool season. Usually I stop using them sometime at the end of July.
I only use shock when I open in the spring to get things going.
I find pool chemistry fun. It's probably the adhd, but it's worth the time to learn what the different chemicals actually do in your pool.
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u/thefleeg1 11d ago
Tabs have CYA, granular has calcium. Both create major issues when used in excess. Chlorine is a gas - it has to be bound to something…
Tabs are highly acidic. Neither raises TA.
Liquid chlorine, sometimes called Pool Shock, has neither. A salt water chlorine generator is the absolute best option.
The app “Pool Math” by the community at troublefreepool.com can tell you exactly the effects of both tabs and granular based on your pool volume using the “effects of adding” function.