What is CYA, and why keep it to a minimum?
CYA, besides known as “ stabilizer ” or “ conditioner ” in the pool industry, protects chlorine from abasement from the ultraviolet ( UV ) rays of the sunday. CYA can be very beneficial up to a point, but becomes increasingly damaging to the pool beyond that. design 1 below illustrates this :
Figure 1: The relationship of chlorine ’ second “ staying power ” and CYA
human body 1 shows us that roughly 20-30 ppm of CYA is enough to give us 95-98 % auspices from sunlight in the first hour, assuming this chart is accurate. This chart does not account for inanimate organics or nitrogen compounds that chlorine still has to oxidize. Figure 1 just shows the relationship of sunlight, chlorine and CYA after one hour. As you can see, the benefits of CYA yield a diminishing return the higher you go. Granted, more CYA can give your chlorine more protection from sunlight for longer, but at what cost ? For that, let ’ s expect at the work of the US Centers for Disease Control ( CDC ) and their inquiry on CYA.1
The CDC ’ s Model Aquatic Health Code ( MAHC )
The Committee that writes the Model Aquatic Health Code ( CMAHC ) released a 2016 update that indicates an amphetamine specify of CYA in pools with a faecal incident. That upper CYA limit ? just 15 ppm. Yes, that may sound depleted, but there are virtual reasons why. See calculate 2, showing how much more free available chlorine you need–with raised levels of CYA–to obtain similar levels of Hypochlorous Acid ( HOCl ) :
Figure 2: Chlorine-CYA Chemistry 101, by Richard Falk
This chart basically shows that more CYA in your water means you need importantly more chlorine to have the same sanitation power. The CDC ’ randomness recommended restrict of 15ppm CYA is not necessarily a ‘ hard limit ’, but a practical one. Just look at how much chlorine ( and acid to re-balance ph ) is required to achieve the desire sanitation solution. To keep water safe, sanitation is critical, and it needs to be hardheaded .
If you have read the Orenda Blog, you already know our opinion of CYA is that it is a double-edged sword. At low levels it provides frightful benefits, but at high levels, boastfully problems. It slows chlorine dramatically, which lowers ORP. The trouble is not stabilization of chlorine, it ‘s over-stabilization of chlorine. here are three relate articles :
Regarding chlorine ’ s ability to prevent alga, the Free Chlorine to Cyanuric Acid ( FC : CYA ) ratio is what matters, not barely detached chlorine. Referring back to Richard Falk, one of the committee members for the CMAHC, you need at least 7.5 % of your CYA level in unblock Chlorine to keep up with alga growth. hera are some examples :
( 100 ppm CYA ) x ( 7.5 % ) = 7.5 ppm FC minimal needed to prevent alga
( 60 ppm CYA ) x ( 7.5 % ) = 4.5 ppm FC minimum needed to prevent alga
Read more: Auto-defrost – Wikipedia
( 30 ppm CYA ) x ( 7.5 % ) = 2.25 FC minimal needed to prevent alga
How do CYA levels get then high gear ?
normally, raised levels of CYA are fair a consequence of habits. sometimes senior high school CYA happens without realizing it. For example, trichlor adds CYA every clock time you use it. It seems like stabilized chlorine use is the chief reason for high levels of CYA. As water system evaporates, CYA stays behind, just like calcium and salt. If you are using a stabilized chlorine like trichlor or dichlor, CYA accumulates … fast. One cypriot pound of trichlor in 10,000 gallons of water will add 6 ppm of CYA. That adds up quickly.
The purpose of this article is to inform people about CYA, its benefits and its drawbacks. We are writing this because we speak to pool professionals nationwide who either do not know about CYA ‘s impact on chlorine efficacy, or do not realize how dangerous it is. We hope this article helps .
CYA ‘s negative impact on the LSI
As if CYA ‘s shock on chlorine were not enough of a rationality to keep its levels to a minimum, there is more. Another relatively misconstrue consequence of CYA is its impact on your water ’ s overall libra. According to the Langelier Saturation Index ( LSI ), CYA matters because it leads pool operators to believe they have more carbonate alkalinity than they in truth do. This is because the LSI convention requires a CYA correction against total alkalinity to find the carbonate alkalinity. It ’ sulfur complicated ( but the Orenda App does all the mathematics for you ) .
All you need to know is the higher your CYA, the lower your LSI. And you might be surprised at barely how impactful CYA is when using the Orenda App LSI calculator .
How to reduce CYA in pools
What can you do if your CYA levels are already gamey ? Can CYA levels be reduced in a pool ?
Yes, the most economic room to lower CYA is to partially drain and dilute the pool with newly body of water. Consult a pool professional if you want to drain more than 1/3 of your water, because there are risks with hydrostatic coerce and other concerns. There are besides some specialized filters that exist to capture CYA and remove it from water, such as overrule osmosis ( RO ). RO is far more dearly-won, but it may be the best option for people in regions of the nation that are ineffective to drain their pools.
It actually just comes down to cost and risk. Significant drain has risks and should merely be done by a pool professional, so dilution over time is frequently the best option. The alternatives to draining your water are to 1 ) pay big money for filtration, or 2 ) attempt to manage the pool with gamey levels of CYA. Neither of those two options are as easy or low-cost as replacing water with bracing water system .
The bed line : keep CYA levels moo enough to manage sanitation and maintain LSI balance. If your CYA is besides high, draining and load is the most price effective means to reduce CYA in your pool .
1 Falk, R.A. ; Blatchley, E.R., III ; Kuechler, T.C. ; Meyer, E.M. ; Pickens, S.R. ; Suppes, L.M. Assessing the Impact of Cyanuric Acid on Bather ’ sulfur risk of Gastrointestinal Illness at Swimming Pools. Water. 2019, 11, 1314 .