Test results w/ SpeedStir and light vs. no light

[minxcal]

I've been testing w/ TF100 and SpeedStir daily. However, it was dark this evening when I got to get out for my FC/pH measure for the evening, so I turned on the extra light. For the first time ever, .5 CC registered... Took another sample of pool water and came inside to do it under normal lights - no pink, so no CC. Have I been missing this all along and the light just brought it out? If so, I'm going back out and retesting EVERYTHING with that light on and turning the pump/SWG on all night! (Like I said, never had CC register, so it's freaking me out a bit!)

BTW - FC was 5, pH was 7.5

 

[JamesW]

0.5 ppm is not something to be concerned about. If it goes to 1.0 ppm, or you are getting excessive overnight loss of FC, then you can consider taking action.

Just maintain the correct FC for your CYA, and you should be fine. You can always raise the FC a little bit if you have any concern about algae or excessive CC. I will usually go to 15 % of CYA if I have any reason to believe it might be necessary.

 

[BoDarville]

Re: Test results w/ SpeedStir and light vs. FC no light

Using the standard CC precision test of 0.5 ppm, it is not unusual to have CC show up on the test, Speedstir light or no light. CC in a well managed pool usually fluctuates in the range of zero to 0.2 ppm. With the standard CC test precision of 0.5 ppm, it is assumed that any measurement of 0.5 actually means the CC level is quite close to zero, but just high enough to show up on the test. A CC of exactly 0.5 is incredibly uncommon. CC either tends to fluctuate around 0, occasionally just showing up on the test, or it tends to be 1.0 ppm or higher. Sitting around 0.4 to 0.5 is quite rare.

The fact that it took only one drop of R-0871 to clear the CC sample means you are good.

 

[minxcal]

Thank you both for responding!

I tend to forget that tone and such aren't "heard" in typed messages - it gets me in trouble at work from time to time. :lol:

I've been through Pool School more than I'd like to admit, so I fully understand that .5 or less is not concerning. I'm more interested in the difference between testing in normal indoor light or daylight vs. the SpeedStir light, especially because I've been fighting high TA since we got the pool. I'm thinking I might go test it w/ the SS just for fun!

 

[spidey07]

I had similar results that alerted me early. I never have CC.

Your FC is low. You have the start of something growing. Nip it in the bud. Raise to slam levels of FC.
Your testing history just said something changed. For me it was increased water temps and presence of CC.

 

[minxcal]

You're saying my FC of 5 is low? That's not how I understand it according to this... pool-school/water_balance_saltwater_generator

 

[JamesW]

5 % of CYA is the minimum for a salt pool. Therefore, you should be good with 5 ppm as long as your CYA is not too high.

 

[minxcal]

FC is actually a tad high for my current CYA of 60. Bumped up the SWG this weekend because we had company. Full test results (done last night - just do TC and pH daily) for those interested.

FC - 5
CC - 0 (though this is in question today!)
pH - 7.5
TA - 120
CH - 320
CYA - 60

 

[JamesW]

I think that you're doing very well. Nothing to be concerned about. You have a good handle on the chemistry.

 

[minxcal]

My high school science teacher would never believe it! Thanks, James!

 

[Patrick_B]

Yours is a prime example of why I don't care for the light. It adds color to the sample and it is not a good thing when you are trying to see the subtle changes of endpoints. My opinion, but I have a lot of experience to back it up. In a lab setting these are usually run on a white or light background with very strong ambient lighting.

Good job on getting a handle on the chemistry. That's what it's all about.

 

[minxcal]

Just for the record, after topping off a bit today, I took a sample to Leslie's to have them test (needed tested for iron and I don't have that one) and their numbers matched mine! Go me!