CYA question

flarfum25 · May 28, 2014

Hello there everyone,

Our pool has recently been opened for the season and all my levels are looking spot-on... except my CYA. I started using the BBB method last summer when we bought the house w pool and have been very happy with it-- love my TF100 kit and all the money I started to save. I cold turkey quit using the trichlor pucks the previous owners had in the garage because my CYA was already good last year, around 60/70 if I remember correctly. By summer's end I was spending a bit more than $10/week on my pool and all my levels were great.

So now I broke out my handy TF100 and all my levels are good but my CYA is showing less than 20, 0 if that's possible. Does it all go away over the winter? I'm confused because I thought I learned last year that using up my leftover trichlor pucks would do me no good because my CYA would continue to go up, and it doesn't leave the pool once it's there. So where'd it go? We took the water level down but we didn't nearly drain the pool.

Anyway, my question today is do I need to go buy the CYA and add it according to your directions with the sock? OR... can I just use up those trichlor pucks now and raise it that way? How quickly could I expect it to raise if I went that route? I hate to just waste something that's already sitting here if it will work for what I need...

Oh and my levels are:
FC- 3.5
CC- .5
TC- 4
pH- 7.6
TA- 60
CH- 8
CYA- <20

woodyp · May 29, 2014

There are situations in which some type of bacteria can actually consume cya over the winter if not actually just convert it to ammonia. Wish I could tell you we fully understood it! Good news is---it didn't go up!

BoDarville · May 29, 2014

Here's another possibility...

Since you just opened, I need to ask this...Did you test the CYA after the pump was running for at least several hours (at least enough for one complete water turnover)? The CYA level can test differently when the pump has not been on in a long time, especially when opening a pool for the season. Other members have reported a similar phenomenon which may suggest that CYA stratifies in the water (e.g., settles towards the bottom of the pool) or that CYA has crystallized somewhere. Considering that you just opened the pool and that CYA is much easier to add than it is to lower, I would run the pump long enough for at least one water turnover (more would be better), retest, and post back with your results.

flarfum25 said:
my question today is do I need to go buy the CYA and add it according to your directions with the sock? OR... can I just use up those trichlor pucks now and raise it that way? How quickly could I expect it to raise if I went that route? I hate to just waste something that's already sitting here if it will work for what I need...

The short answer is yes, you can use trichlor pucks to increase CYA. However, they are better used to top off the CYA as opposed to adding a significant amount all at once since the pucks dissolve very slowly. For adding larger amounts, the granular CYA-in-a-sock method is the preferred way. The granules should dissolve within 2-3 days in most cases which is considerably quicker than the pucks.

flarfum25 · Jun 3, 2014

I was wondering why nobody ever responded to my question and decided to come on here and try asking again-- and it turns out there were replies after all! So thanks guys, and my apologies for not responding sooner. Last year when I posted, responses came to my email so I just assumed they would again this year. Maybe I have to request that somewhere...

Anyway, the answer to how long I waited was actually a few days after the opening. With the pump running for about 8 hours each day. And I have been testing the chlorine and pH daily, along with one other CYA test 2 days ago-- same results. I've had to add a half gallon of bleach several times already, although not every single day. We are about to get more sun here though, and more regularly, so that will surely go up a good amount. I will go buy some CYA and do the sock method.

Should I be worried about whatever bacteria could be in there consuming my CYA over winter?

woodyp · Jun 3, 2014

If it got consumed once, it will probably happen again. Just be aware that it CAN! Low cya over the winter won't make much difference anyhow until opening.

frustratedpoolmom · Jun 3, 2014

So just a guess but you lowered the water level to winterize - you have a mesh cover, pool was probably full when cover came off? That's plenty of dilution to lower the level down to 20 or so.

flarfum25 · Jun 4, 2014

Oh, YES!!! Not only was the pool full when we took the cover off, but we had to take the cover off in February and pump some out bc it was so high!
Very clever, frustratedpoolmom, thank you!!! : )

Whew!

Just another quick question-- according to the pool calculator, I need to add at least 72oz of CYA to get to a good place (since I don't know if I have 0 or 10 currently and depending on if I want to get to 30 or 50). Does 72oz sound like a normal amount? Seems like a whole lot to me but I obviously am basing this on... absolutely nothing, ha. Just seems like a big number for some reason.