Increasing CYA

[Wade C]

Greetings All,

Just finished a Pebble Tec remodel on the pool, and after the refill (city water) I'm looking at the following numbers: FC: 3 / PH 7.5 / TA: 90 / CYA: not registering. CYA before the remodel was always relatively high (80-90), so I'm in uncharted waters - pun intended - here. I guess I could just throw in a couple of chlorine pucks and wait for the inevitable increase, but the idea of dropping pucks into my pool bothers me for some reason. So here's my question(s): Is a CYA below 30 really bad? Do I just get over it and add the pucks, or is there alternate methods? If pucks are the answer, anyone have any idea on how many it will take to get me into the good (30-50?) zone? Thanks in advance for the recommendations!

Wade

 

[JVTrain]

Pool Math is your friend. Input your pool volume and it will let you know how much CYA you need to add to get to your target, if you're going with adding CYA, not pucks, which I would recommend. Use the sock method to add the CYA either in a skimmer or hang in front of a return. Don't assume your CYA is 0 though, it's just less than 20. Assuming it's 10-20 is safer when targeting your desired CYA.

CYA below 30 is bad because you'll be wasting chlorine. With low CYA, sunlight will chew up your FC faster, especially in Florida. Are you using a SWG or manually chlorinating with bleach? If manually chlorinating, I would suggest your CYA at at least 40, 50 probably better. If SWG, then you're looking at the 70-80 ppm range.

You can also use Pool Math to determine how much a single puck of trichlor would add in CYA but using the Effects of Adding Chemicals section at the bottom. Most trichlor pucks are 8 ounces in weight iirc.

 

[Richard320]

Tap water has zero CYA in it, so it's not surprising your test comes up empty.

Pucks take too long to dissolve to rely on them alone to raise CYA. Using Effects of Adding Chemicals in poolmath... 5 lbs of trichlor will raise FC by 55 and CYA by 33. Assuming you could control the dissolving rate to keep it at 2 FC per day or so, it will take a month to bring CYA up. Trichlor is also very acidic, so you might find yourself actually low on pH and TA and then you'll need to add chemicals to fix that.

On the other side.... One 4 lb canister of CYA granules should bring you up to 48 CYA in a matter of days. You'll lose a little due to splash out but you still have a little room to use pucks should you leave town for a week or so somewhere down the line. 60 CYA would not be excessive in Florida.

 

[borjis]

AS Joel pointed out you do need the CYA for sun protection. Indoor pools don't need cya.

My pool is just slightly bigger than yours and 3 lbs of CYA made it 30 ppm

 

[Wade C]

Thanks to all for their responses and recommendations, I didn't consider that there might be such a thing as CYA granules. Problem solved...as always, the folks at the TPF forums rock!