Does cold water temperature affect chlorine test?

Jun 25, 2014
5
My pool is clean and up and running at a temp of 50. Just opened it last week. There is plenty of salt in it - my test said 3200 ppm (although the chlorinator's low salt light is on). When I add the DPD powder to test for FC the water stays totally clear. Last week (water was 56degrees) I had FC of 4. Is it possible that my test this week is not reliable due to the cold temperature? Could the powder have gone bad in the past week? Or is it accurate that I have no chlorine? The CYA level is also coming up as 0 (unmeasurable below 30). I've been maintaining my pool for 2 full years and this is a first for me. Thanks in advance!!!
 
Most SWG do not produce when water is that cold. I would think you very well may have no chlorine in the water and could use some liquid chlorine to spike it up until the water warms more. I'm sure that's also why you're seeing the low salt light.
 
Short answer: no.

Long answer: many SWGs shut off at low water temperature, so you may not be producing any FC. If none is being produced, whatever you had will be long gone in a couple days. Cold water will slow the reaction in the CYA test, which can make you read falsely low. Scoop up a water sample and bring it inside and let it warm up to room temperature at least. Maybe set it in a sunny windowsill. Let the sample warm up before you mix it and then carry it outside into full sun and recheck that CYA reading.
 
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