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Thread: Cost Comparison of Cyanuric Acid (CYA) Sources

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    Join Date
    Mar 2007
    San Rafael, CA USA

    Cost Comparison of Cyanuric Acid (CYA) Sources

    This thread is a companion to the Cost Comparison of Chlorine Sources thread here. This thread compares the costs and pros/cons of different methods of adding Cyanuric Acid (CYA) to the pool.

    Cyanuric Acid is sold at Leslie's online here for $36 for 8 pounds or $4.50 per pound [EDIT] see posts below for prices as low as $3.10 per pound [END-EDIT]. It is nearly 100% pure, but dissolves very slowly and is somewhat acidic. If put into a sock or panty hose and hung over a return flow or put into a skimmer sock in the skimmer (with the pump running 24/7) it can dissolve in a day or two instead of a week [EDIT] see posts below as it can dissolve faster than that if physically squeezed and helped along [END-EDIT]. One pound of CYA increases the CYA by 12.0 ppm in 10,000 gallons.

    Natural Chemistry's Instant Pool Water Conditioner shown here has one gallon add 40 ppm CYA to 10,000 gallons. It is sold at InTheSwim online here for $25 per gallon. It readily disperses into water and is relatively pH neutral -- slightly alkaline.

    From the chlorine cost comparison thread, Trichlor is $2.20 per pound while Dichlor is $2.60 per pound. One pound of Trichlor increases the FC by 11.0 ppm and the CYA by 6.7 ppm in 10,000 gallons. One pound of Dichlor (dihydrate) increases the FC by 6.6 ppm and the CYA by 6.0 ppm in 10,000 gallons.

    So the cost per 1 ppm CYA in 10,000 gallons is as follows for each source:

    Cyanuric Acid ........................... $4.50 / 12.0 = $0.375 [EDIT] $3.10 / 12.0 = $0.258 see posts below [END-EDIT]
    Instant Pool Water Conditioner .... $25 / 40.0 = $0.625
    Trichlor ...................................... $2.20 / 6.7 = $0.328
    Dichlor ....................................... $2.60 / 6.0 = $0.433

    I need to add the cost of Borax to compensate for the acidity of Cyanuric Acid, Trichlor and Dichlor (I'll edit this post later), but essentially you can see that Trichlor is least expensive and you get addition of chlorine as well, but it is slow to dissolve. Dichlor is fast dissolving and you also get chlorine so is probably the most economical way to quickly add CYA.

    For the 1 ppm CYA rise in 10,000 gallons, Cyanuric Acid needs 1.7 ounces weight of Borax to maintain pH. Trichlor, after chlorine gets consumed, needs 8.0 ounces weight of Borax to maintain pH. Dichlor, after chlorine gets consumed, needs 3.8 ounces weight of Borax to maintain pH. I found 20 Mule Team Borax for $4 per box (76 ounces) on Amazon. So one needs to add $0.09 to the Cyanuric Acid price, $0.42 to the Trichlor price, and $0.20 to the Dichlor price for a more accurate comparison.

    If I use Arm & Hammer Super Washing Soda instead of Borax, then Amazon sells a 55 ounce box for $2.70 (shipping is high, but some grocery stores had it for this price as well). In this case pure Cyanuric Acid needs 0.86 ounces weight of Washing Soda, Trichlor needs 4.0 ounces, Dichlor needs 1.9 ounces. So one needs to add $0.04 to the Cyanuric Acid price, $0.20 to the Trichlor price, and $0.09 to the Dichlor price.

    Another alternative for raising pH and similar to Borax in not raising the TA as much is Lye (Caustic Soda) which can be obtained for around $3 per pound. For the amounts as indicated above, pure Cyanuric Acid needs 0.35 ounces weight of Lye, Trichlor needs 1.6 ounces while Dichlor needs 0.77 ounces, so this adds $0.07 to the Cyanuric Acid price, $0.30 to the Trichlor price and $0.14 to the Dichlor price. So this is less expensive than Borax, but more expensive than Super Washing Soda.

    To be fair, we should subtract the price of the least expensive chlorine from the Trichlor and Dichlor since you do end up adding both chlorine and CYA with these sources. From the chlorine cost comparison page, the cheapest source of chlorine was Trichlor (not counting the Borax required to maintain pH) so essentially using Trichlor pucks/tabs to add CYA it costs incrementally $0.42 which is still higher than pure CYA. Dichlor incrementally costs $0.433 - $0.328 + $0.20 = $0.31 (or $0.20 if using Washing Soda for pH adjustment) so not that much different than pure CYA (depending on where you get it).

    So considering everything, both pure CYA and Dichlor are reasonable alternatives, with the latter being reasonable when you aren't in as much of a rush and can increase the CYA as part of regular chlorine addition (or for shocking, if that was to be done anyway). Of course, going away on a trip and using Trichlor pucks in a feeder also work (more expensively) if one is not in a rush to increase CYA quickly. Sounds like a personal choice to me.

    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA
    In my area, Home Depot has 5 lbs of CYA for $18 or $3.60/lbs. The cheapest place that I have found so far. I think Lowe's has it for the same price as well. According to the label, it is 100% pure.

    Also, I was able to dissolve about 5 lbs of CYA in 2 hours today. I used three skimmer socks in with a leaf rake over a spa spillover. Every half hour I went out and squeezed the socks a bit and after about 2 hours, all of the CYA had dissolved. I have found that once the CYA is wet, the mechanical process of squeezing the socks really speeds up the process. If had gone out every 15 min, I think I could of halved the time.

    BTW, I am increasing the whole pool to 80 ppm to see if the extinction rate goes down enough to warrant the higher CYA. I have been running 3 ppm with a CYA of 45-50 ppm so it will be interesting to see how much the residual chlorine will increase with the same SWG settings. If you remember, the spa testing I did showed a significant decrease in extinction rates at 80 ppm but I wanted to try it in the whole pool to see if it is the same.
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    You know, I have been finding my little tiny town hardware store has had the best prices on most of this stuff. Maybe not cheaper than WalMart, but cheaper than Lowes/Home Depot and the pool stores. And considering it is 12 or more miles closer than all the other places, I save money on gas, too. They had CYA @ $15.50 for 5 lbs. Their price on filter sand was slightly cheaper than the pool store and LOTS cheaper than Lowes (I walked out of there laughing when I saw the price for sand). I can also get the 2.5 gallon carboys of 10.5% chlorine at the local hardware for $3.95 a refill.
    Current Pool: IG Concrete / 11,000 gal. / Sand filter / Solar heat / Hayward CL200 / Screened / TF Testkit
    Pool owner since 2001. Thanks TFP for helping me convert off Baquacil after six years!

  4. Back To Top    #4
    I bought 4 lbs. of 96% CYA at Wal Mart for about $13. I disolved it in a nylon knee high in the skimmer. It took a while to disolve however, the CYA level results were accurate based on the amount of CYA I added.
    20 x 40 Clayton & Lambert Stainless Steel Wall and Concrete bottom Epoxy painted 40,000 gallons
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    Re: Cost Comparison of Cyanuric Acid (CYA) Sources

    Since I'm unfamiliar with CYA prices in my area, I just ran a telephone survey in the Silicon Valley for CYA chlorine stabilizer/conditioner:
    1. Lowes: $14.96/4 pounds ~= $3.75/pound
    2. Home Depot: 19.92/5 pounds ~= $3.85/pound
    3. Amazon: = $15.47/4 pounds ~= $3.87/pound
    4. Leslies: $42.99/8 pounds ~= $5.38/pound
    5. Any other suggestions for the Silicon Valley?
    [Note: All prices verified online, see links above if you wish to price match one store with another to save driving.]

    This thread is wonderful for people like me who, (a) need to add a dozen or more pounds of cyanuric acid to our pools, and who (b) are unfamiliar with 'standard' prices. It also is useful for those few like me who (c) have large leaks to deal with (and therefore who have to continually add CYA).

    Luckily this survey doesn't take any gasoline - just a few phone calls, to find the best price in your area. Also fortuitously, many stores (e.g., Home Depot vs Lowes) price match - so if one is closer to you, simply print out the links above and show it to them. In addition, given CYA isn't something you always need right away, with this information, you can combine trips if/when the best price is to a big box store that you don't often visit.

    Remember: It's your duty to buy the lowest price ... otherwise, you're the reason for the higher prices for everyone else! (microeconomics 101)
    Silicon Valley, 38,500 gallons in-ground plaster; Sta-Rite System 3 Model S8M150, 259 sqft cartridge 25022-0203S + 191 sqft cartridge #25021-0202S = 450 sqft filter@0.28gpm/sqft = 125 gpm@50psi max. Three 220v Sta-Rite Max-e-Glas II pumps {AO Smith QC1102 1.0x1.65SF for filter + cleaner; SQ1152 1.5x1.47SF for spa jets; square 48Y flange}. 13 Fafco 12'x4' professionally installed "Revolution" solar heating panels + Raypak RP2100 P-R 405A-EP LPG 399,000/hour heater + Compool Lx3600 controller + Infinity 4000 automatic pool cover (120v 3/4 HP motor); both skimmers are NOT filtered & serve only as intake for 9-port water valves (aka cleaner heads) controlling fifteen Paramount PCC2000 3" self-cleaning jets with the optional Debris Containment Canister.

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    toadlife's Avatar
    Join Date
    May 2009
    Lemoore, CA

    Re: Cost Comparison of Cyanuric Acid (CYA) Sources

    I bought some CYA tonight at Kmart. 3lbs for $13.99 ($4.66/lb)

    Not a great price, but the other stores are ten miles away and I only add it once a year.
    21,000 Gallon IG Plaster with Spillover Spa (Built in 1978) | 48 sq/ft Hayward DE Filter | 3.0 HP Pentair Variable Speed Pump | Hayward H250FDN Heater| 8 Gallon Liquidator | Taylor K-2005 | Taylor FAS-DPD Chlorine Test | Taylor "SpeedStir"

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    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Cost Comparison of Cyanuric Acid (CYA) Sources

    I think this last post really does sum things up, while this may be a nice academic topic, in the real world this is a product that gets added once or twice per year in any quantity and the money spent on gasoline comparison shopping is likely to cost more than any savings a person may see.

    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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