CYA = Zero

[Longgrove]

What's the current thinking on CYA levels? I just did a partial water change (over 50%) and CYA is zero. Thanks

[Watermom]

We usually suggest somewhere between 30-50.

[EricH]

Why? Any harm in a zero CYA other than chlorine loss in the sun?

I have a translucent cover that is on if we're not in the pool, and trichlor pucks in a feeder for nightly chlorine dosage (pump only at night due to time-of-use electric rates.) I only shock at night, using bleach or cal-hypo.

[chem geek]

EricH,

It's not just that a zero CYA won't protect the chlorine from sunlight, but that the disinfecting chlorine level will be too high and will be more corrosive to metal, swimsuits, skin, etc. Indoor pools without CYA are like that, though they usually try to run at lower FC (2 ppm or so).

In this post you also mention no CYA even when using Trichlor which doesn't make sense. If you had no CYA in your water, then your FC would drop in half in about 30 minutes in direct noontime sunlight and it seems that this is not happening for you even with the limited amount of sun exposure. I suspect you do have CYA and for some reason it is not getting measured.

Richard

[EricH]

Interesting information, thanks. Didn't realize CYA helped with the corrosiveness of the water.

The pool is usually covered when the sun is out, but I do occasionally have to fight to keep FC up, so who knows.

To clarify though, even if my tests aren't catching it, I shouldn't need to add raw CYA if I'm using trichlor tabs in an auto-chlorinator (which runs all night.) The CYA must be getting in there, and my understanding is that once it's in there, it doesn't go away until you dilute the water.

Love the forum!

E

[terrymoots]

Hello!
Not sure if I should start a new thread or continue on this post....

Keep losing chlorine level. Just checked CYA with Taylor test kit and boy, there sure doesn't seem to be any CYA in the pool! Test tube doesn't record below 30 ppm so I am assuming there is VERY little CYA in the pool.

Pool is very cloudy. Added three 182 oz. jugs of bleach last night. This morning readings are:

FC - 2.5 ppm
TC - 2.5 ppm
CC - 0 ppm
PH - 7.8
Alk - 90
CYA - below 30 ppm

Added another two 182 oz jugs of bleach just before posting this thread. Vaccumed pool. Hope to clear by tomorrow and enjoy this glorious sunny weather. Going to the pool store now to buy stabilizer. Any thoughts on how much to add (I've read in the forum not to add too much) and any other suggestions.

My pool has always been sparkling but realize CYA might be the culprit here. Have had the pool 3 years and never added CYA. The pool came with the house. Thanks again and happy summer! t

[chem geek]

If you truly don't have any CYA in the water (i.e. if the CYA test doesn't even get cloudy at all), then your chlorine is likely burning off to zero at some point during the day so the cloudiness could be a nascent algae bloom.

You have several options for adding CYA to your pool as follows:

1) You can buy Cyanuric Acid (CYA) directly and put it in a panty hose or sock you hang over the side of your pool in front of a return. This will have the CYA dissolve in a day or two instead of taking a week.

2) You can temporarily switch to using Trichlor slow-dissolving tablets/pucks as your source of chlorine, but they are very acidic so you will need to add pH Up / Arm & Hammer Super Washing Soda / Sodium Carbonate periodically. For every 1 ppm FC from Trichlor you get 0.6 ppm CYA. This is an inexpensive option when accounting for the price of both CYA and chlorine.

3) You can temporarily switch to using Dichlor granules which quickly dissolve. This is also an acidic source of chlorine (after chlorine gets used up), but not as much as Trichlor. For every 1 ppm FC from Dichlor you get 0.9 ppm CYA. This is a more expensive option, but is convenient.

4) You can use the Natural Chemistry product called Instant Pool Water Conditioner found here. This is essentially CYA in a different form that is fast-dissolving. It is more expensive than pure CYA in option #1, but is more convenient.

It is important to not add too much. Try and target 30 ppm CYA and see how that goes for you. You can always add more if the chlorine seems to be burning off quickly, but higher CYA levels require higher FC levels to compensate (see Ben's Best Guess CYA chart).

Richard

[terrymoots]

Thanks.

I opted for option 1 and added 2 lbs of chlorine stabilizer (which is 100% cyanic acid). I disolved the granuales in warm water and added to the skimmer...I will keep monitoring all pool levels. Thanks again, t