How Do You Lower CYA?

[cheshamjim]

Here are my test results for my very first test with my just-received RS234 test kit:
FC = 11
CC = 0
pH = 7.2
Alk = 140
Cal = not tested
CYA = >100 (fills 1st inch of view tube, then dot disappears)
My CYA reading dictates that my chlorine content should be maintained between 8 and 15 ppm acccording to the Best Guess Table. I'd like to lower my CYA so that I wouldn't have to maintain such high levels.

I've stopped using stabilized products (dichloro and trichloro) and hopefully this stems the advance. But how do I get it to go down?

-Jim

[JohnT]

Drain water and replace, unfortunately:(

[Sherra]

I'd do a 50% drain & refill then re-test your CYA...if it's still higher than you want it, then do another 50% drain & refill. A 50% drain/refill should lower your CYA by 50%.

[cheshamjim]

Thanks, all. I was afraid this is the answer I'd get.

It seems that with my installation, I can only get by with a 30% drain at any one time. Think I'll wait until its time to close the pool.

-Jim

[Sherra]

One option is to get a really big plastic tarp (wide enough & long enough to cover your pool plus about 10 feet added to each measurement...just the cheap roll you can get at any home improvement place for a few bucks) and use that as a membrane between the two layers of water (the pool water beneath and the fresh water on top). You can theoretically do a 100% drain/refill that way without any damage to your liner. It's been discusses several times on the board. I don't know if anyone's actually DONE it on the group, but I remember seeing that someone had SEEN it done.

[cheshamjim]

Sherra, what an intriguing idea!

As I first envisioned this, one would introduce fresh water onto the membrane (tarp) which has been spread over the pool. As the water accumulates on the top side of the tarp it would sink and gradually displace the old pool water while complying with the sides and bottom of the pool.

Can this be? I am not a physicist or an engineer, but both the old and the new water would be essentially equal in mass, so it wouldn't seem that one could easily displace the other. Perhaps the old water is pumped out at close to the same rate fresh water is introduced to the tarp.

If this all worked out, how in the world would one remove the tarp once the pool is refilled? Have I correctly understood what you were suggesting?

If there is a tried and true procedure, I'd appreciate reading about it.

-Jim

[reneep]

Great Idea. I am sure it will work as over the winter when I cover my pool and we get a rain it displaces the pool water. When I siphon off the rain water, I have to add water back to the pool. Just cover with cheap plastic, fill then cut holes in it and pull it out by section... new water in pool to replace old ???

I am in the same boat and have been draining about 4 inches, refilling, letting the pump run to circulate and repeat. This seems much more effective.

[Watermom]

Fill with fresh water on top of the plastic sheet and pump out the old water from the bottom of the pool.

[let_her_flicker]

Another option is to run a high cya pool. You do not have to drain. Just make sure you have Ben's kit and keep the cl at the appropriate level. It should not be an issue. In fact, it may be easier as the cl will be used up at a slower rate because of the high CYA. Check your cya every two weeks and adjust accordingly.

If you are chlorinating with liquid bleach, you cya will go down. If you are using stablized tablets, it will increase. Just because you cya is high doesn't mean drastic measures. Let it go down naturally and you don't have to waste water.

Back on the old forum, this was discussed and sometimes advocated as a way to operate your pool. To do this you will need Ben's kit. I hope this helps.

[cheshamjim]

let_her_flicker, I like your suggestion. You say that as long as I don't use the stabilized tablets, the CYA will go down naturally. As of two weeks ago, the only sanitizer I have used is bleach (Chlorox from a Sam's Club).

I think that the fact I have used the tablets and powdered "shock" since my pool was first opened 4 seasons ago has caused my CYA problem.

As long as I know the CYA will go down on its own without these "stabilized" products I can wait. Patience, after all, is a virtue when trying get pool water right.

Thanks for your help.

-Jim

[waterbear]

It can take a very long time for the CYA to go down on it's own, expecially if you have a cartridge filter. CYA will only go down by dilution under normal circumstances. This means refilling from splashout, backwashing a filter, or draining and refilling. Evaporation will merely concentrate it and it will dilute to where it was before when the evaporated water is replaced. Using bleach or any other non stabilized chlorine will not make it go down. However, using trichlor or dichlor will make it rise since with every use of these products you are adding more CYA!

BTW, most powdered shock is Cal Hypo (calcium hypochlorite) and is non stabilized chlorine. Dichlor is ususally only recommended for shocking spas which get drained and refilled every 3 months. It is ususally used in poos for normal sanitation.

[gordyjamz]

Last year I was running with cya of 60-70, but when opening this year I noticed it was down to 30. This was before I refilled back to normal level, at which point it was down to under 20. I had to actually raise it. I think it goes away when the water sits over the winter. So it may be less hassle to just run with higher cl level this year and see where you stand next spring and adjust accordingly then.

[crackerjack]

In The Swim has cyanuric acid remover that is capable of removing 30-50 ppm of cyanuric acid in 10,000 gallons of water.
At $50 a gallon, not sure if it would be worth it though.

[Watermom]

This has been discussed on the forum before and it is not recommended that this product be used.

[let_her_flicker]

Do not add any CYA remover. It will only make matters worse.

Waterbear is right about the evaporation and I should not have mentioned that. I also should have worded my response clearer by stating that by using bleach you are not adding anymore CYA. I was including the fact that you will have splash out and rainfall which dilutes concentration in your pool.

Watch out for the powder shock. Some are 4 in 1 shocks that have stuff in it your pool doesn't need. You can shock just as easily with liquid bleach.

Patience is the key with this issue. If you don't like your CYA level when you open next year, you can always drain a little more water away.

Another item that will lower your CYA is when you vacuum your pool, do it to waste. Then you are removing a small amount of CYA and when pool water is replenished either by hose or by rainfall it will not have any stabilizer in it.



Sorry for the confusion. Good Luck

[waterbear]

In The Swim has cyanuric acid remover that is capable of removing 30-50 ppm of cyanuric acid in 10,000 gallons of water.
At $50 a gallon, not sure if it would be worth it though. It removes the cya by causing a precipitaton reaction that turns the water very milky. It is melamine, exaxtly the same as the reagent used to test for CYA in our test kits. You know what that tester tube looks like with high CYA levels...imagine your pool looking like that for a week! Also, from what feedback I have heard about CYA reducers/removers...they lower the CYA more in the range of 20 ppm per 10000 gal. Do the math. A water change is cheaper (and will probably take less time!)

[aquarium]

A water change is cheaper (and will probably take less time!)

I'm sorta surprised that a water change isn't recommended here more often. I see a lot of people throwing a lot of chemicals and/or bleach at problems, when a simple water change would solve things right away. Gets you back to a known baseline.

TW

[cheshamjim]

I checked the label of my old (never-to-be-used-again) sanitizer, a hugely expensive product from BioGuard called Smart Shock. It is 63% sodium dichloro-s-triazinetrione. Using this stuff for 4 plus years, along with "Smart Sticks" (slow desolve tablets) is probably the source of my CYA problem.

Water drain and replacement may be an easy solution for many pools, but my vinyl lined pool doesn't like to be drained. I drained about a third of my water earlier this year and ground water caused the sides to billow inward. Thank goodness everything went back into place when refilled. But my draining problem is why I was so interested in the idea of a membrane (tarp) to aid the process. I think I'll post something on the Pool Construction and Repair forum on the subject.

Thanks everyone for your suggestions. I am always amazed at how useful this forum is.

-Jim

[let_her_flicker]

I'm sorta surprised that a water change isn't recommended here more often. I see a lot of people throwing a lot of chemicals and/or bleach at problems, when a simple water change would solve things right away. Gets you back to a known baseline.

TW

Some people live in places where you just cannot dump 5 or 10 thousand gallons of water into their yard. Drainage can be an issue where it goes into a neighbors yard, etc. Without knowing the particulars of a situation it is easier to add those "low cost" grocery store chemicals to solve the problem.

[aquarium]

Ah, okay. I guess we're 'lucky' to live in a drought area. :p

That's a special challenge, the caving walls, that vinyl pools present. It would seem to me that that makes the trichlor pucks completely unsuitable in that case. Wonder how many pool companies tell people that. :rolleyes:

TW