CC bouncing around - is it me?

[wisco]

Hello All,

Pool noob and TFP noob here. Bought the place last Summer so this is my first full season with it. Just switch from puck and pray to TFP about three weeks ago. So far seems to be going quite well. But one thing I'm wondering about is my CC readings. But I guess I'm getting ahead of myself, here are my test results for the last three days.

7/1 7:06pm
PH 7.6
FC 6.2
CC 0.4
TA 90
CH 200
CYA 60 (ish)

7/2 5:48am
PH 7.6
FC 7
CC 0.0
TA 90
CH 200
CYA 60 (ish)

7/3 8:05am
PH 7.7
FC 5.6
CC 0.2
TA 90
CH 200
CYA 60 (ish)

So I'm targeting FC 8 because until I get my R-7065 and calibrate myself, I'm not real confident in my ability to play hide the dot. I'm curious about the CC readings. Is, for example, moving from 6.2 to 8 enough to hit the breakpoint? That's certainly not the only time I've noticed this happening over the last few weeks; is it user error? The CC test I took today (7/3) I think did show the scantest of pink with the R-0003 but not as much as normally one drop of the R-0871 seems to clear up.

So is this reasonable or am I messing something up?

 

[JoyfulNoise]

Welcome to TFP

I would say that your CCs are fine. The test has a 0.2ppm tolerance to it and it is certainly reasonable to see a 0.2ppm fluctuation in CCs based on bather load, leaves, dust, pollen, etc.

Do you have an SWCG? Your CYA is a bit high for a manually chlorinated pool but nothing to worry about. It will come down naturally with dilution/splash out

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[wisco]

Thanks, JN

Do you have an SWCG? Your CYA is a bit high for a manually chlorinated pool but nothing to worry about. It will come down naturally with dilution/splash out

No it's not SWG. And yeah, CYA is higher than I guess I'd like. That stems from from heavy trichlor use for the few months last year and a couple weeks after I opened this year until I decided to turn off the chlorinator and go this route. I'm going to try to just go with it this season rather than refill since I do a partial drain when I close. So far so good. Haven't seen any indication I need to SLAM.

 

[JoyfulNoise]

Great.

As long as you maintain the proper FC for your CYA and do not let the pool drop below the min FC, then there isn't much chance you'll ever need to SLAM it.

Manual chlorination is practiced by many but it can get tedious after a while and there's more opportunity to miss a dose. Perhaps you can trawl the TFP Automation Threads and think about possible adding automation to your pool (SWG or Stenner pump).

Enjoy the swim season.


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[chem geek]

Do you use a pool cover? If so, uncover the pool at least once a week to expose the pool to sunlight and your CC should remain low. I wouldn't worry about the CC so long as it stays <= 0.5 ppm and you don't notice any "bad pool smell". If you aren't using a pool cover so have sunlight on the pool and you don't have any pollen getting blown in or had a high bather load (pool party), then I think your CC measurements may have some user error. Even when done correctly they are only +/- one drop (or 10% of the reading, whichever is greater) which with a 25 ml water sample is 0.2 ppm.

 

[wisco]

Yeah, think over the winter I'll look into an SWG. Getting a little help on the chlorine front would be nice and the idea of the salt making it a more comfortable pool is attractive too.

The thing about doing the chlorination myself is the peace of mind knowing I reacting to exactly what the pool needs at a given time and not fiddling with that dial hoping it's working. Thanks again for the advice.

 

[wisco]

@chem geek,

No, no pool cover and it gets about 4-6 hrs of direct sun a day. But yeah as for pollen etc. I've got trees right on top of the pool. There are leaves and other arboreal cast-offs in it everyday. Would you ever go up to a 50ml sample to get a finer tuned reading? If I tried that would I need 10 drops of R-0003 rather than 5 for the 25ml? Or does it work like that?

 

[chem geek]

It does work as you describe (you'd also need to use more scoops of DPD powder), but there's no point in getting that fine since other sources of error creep in. Most people go the other way using a 10 ml water sample for a 0.5 ppm resolution which is good enough for most purposes and you use less reagents. In that case, you'd always be seeing <= 0.5 ppm CC so would not be worrying about it.

 

[wisco]

Gotcha, will keep on keepin' on as long as everything stays within tolerance. Thanks.