The Battle between FC and CYA

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thebigwoo

thebigwoo

0
Apr 29, 2017
28
DAYTON, OH
Hi all ... so in attempting to figure out how to strike the proper balance between FC and CYA levels ... what do you do?

We have a Hayward inline auto-chemical feeder, and right now our CYA level reads 70, which I believe is high. This seems to be the hardest part to manage when it comes to pool upkeep. Everything else we have been able to figure out, and balance and make adjustments. But with the CYA, i feel like we're in a loosing battle. We need to put chlorine in the pool, but don't see an effective way to do it on a consistent basis without using the tabs/feeder. Everything I have read so far sounds like there aren't tabs available that don't have CYA.

Looking for help suggestions on how to maintain the balance.

Here's our numbers from this morning's readings:

FC = 6
PH = 7.2
AK = 80
CH = 150
CYA = 70

Thanks!
 
Stop using powdered/stabilized chlorine and switch to liquid chlorination. The balance between FC and CYA is simple - always maintain a minimum of a 7.5% FC/CYA ratio. So, for 70ppm CYA, your minimum (floor) FC is 5.25ppm, so call it 5ppm. Always stay above 5ppm FC and you'll be fine. In your pool volume, one standard bottle (121oz) of 8.25% laundry bleach (Clorox) will raise your FC by 5ppm. Since a clean pool loses anywhere from 2-4ppm per day, you'll need about 1/2 jug of bleach per day to maintain your FC levels.

If manual chlorination is too time consuming for you, then invest in either a salt-water chlorine generator OR install a Stenner liquid chlorine pump to inject chlorine every day.
 
If you want to put more $$$ into the pool equipment you could consider converting to SWG which is even easier to manage than the inline feeder imo. I never tried to maintain my pool with liquid but I've heard some on this forum got a stenner pump to automate it. I can say having run my CYA up over 200 with my inline feeder that I'm really glad to not have the issues that come from high CYA anymore. So there are other options...
 
As Matt pointed out, the ratio of FC/CYA is well known, but many in the pool industry just teach what they were taught and ignore the science behind it.

In it's natural state, chlorine is a gas. Many large commercial pools actually use gas injection systems to chlorinate their pools. Now, to change chlorine into something we can use at home it needs to be bound to something to turn it into a solid. The "somethings" that are commonly used are stabilizer (also known as CYA), calcium, lithium, or --- get this water. All of these add a little salt to your water, but they add something else. Cal-Hypo add calcium, Tri-Chlor and Di-Chlor (tabs and most granules) add stabilizer, Lithium hypochlorite adds lithium and liquid chlorine adds - water.

All of these things can be bad for your pool (except the water) in large quantities. The stabilizer helps shield the chlorine from UV degradation, but at higher levels it also impairs the ability of chlorine to do it's work. The higher the stabilizer level you have the higher the amount of chlorine you need. Too much calcium and you start to get scaling on the walls and floors of your pool.

So, why do pool stores push these products? Several reasons.

- Money would be the first. Unless a pool store is in Florida, Arizona or other year round areas they must make their profit in a short swim season. So, they need to sell you as much as they can as quickly as they can. Additionally, chemical sales is their bread and butter. Profit on a bucket of tabs is much higher than on a gallon of liquid.

- Secondly, we are an immediate gratification society. We want a magic potion that will fix our problem right now. This is where the industry has tried to ad items like clarifiers, floculants and the like which in a perfect world help get the bad stuff out of the water quickly.

- Third in my book is training. Most pool store employees learn on the job or through seminars taught by chemical salesmen. So, bad information is handed down from employee to trainee and the chemical salesmen teach them to push high profit items. This is especially true in large chain stores where employees are paid commission and managers jobs are based on how much product flows out the door.

Pool store methods can work for a long time and many people are oblivious to what is happening in their pool. As the year progresses you find that you get a few spots of algae popping up. The store sells you a potion and tells you to "shock" the pool. The algae goes away for a while, but eventually comes back. The potion/shock method is followed again and again until the pool is closed for the year.

Then, if you are in an area where your pool is drained down a lot each winter and winter snow/rains fill an overflow the pool each spring you are starting with a blank canvas, chemically speaking.

It's funny to hear folks who follow these methods say something like, "I had a good year, I only had algae outbreaks three times" like having algae is to be expected.

TFP didn't create the methods we use, but we have fine tuned them to make them as "Trouble Free" as possible.
 
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