Always test water with pump running!

[tcat]

I wasn't thinking and tested my FC about 15 minutes after my pump shut off. Got a "1" reading and I panicked, it'd been so good all week. So I turned on the pump and rechecked in 30 minutes, was "6", just what it should be. I was really surprised chlorine settles to bottom that fast. Another lesson learned

 

[burine]

Or maybe the sun "eats" the stuff at the top first? I guess I should start my pump when I test, I usually test when I get home from work and the pump only runs at night.

 

[jblizzle]

Pump should be running for at least 30-60 before any test. And at least an hour after any chemical addition.

It is annoying that I am not home when the pump runs for solar. So I have to turn it on again in the evening, wait, test, add, wait, turn it off.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[duraleigh]

While it's a good idea to test with a well-mixed sample, chlorine does NOT settle to the bottom. It stays in solution and will be distributed evenly throughout the pool. I can't answer why your tests were so different but want to emphasize that chlorine (nor any of the other parameters we test) does not settle to the bottom.

 

[Richard320]

I wasn't thinking and tested my FC about 15 minutes after my pump shut off. Got a "1" reading and I panicked, it'd been so good all week. So I turned on the pump and rechecked in 30 minutes, was "6", just what it should be. I was really surprised chlorine settles to bottom that fast. Another lesson learned

The sun degrades the stuff faster at the top. Maybe you need to stick your arm a little deeper into the pool when you grab a sample?

I use a 4' piece of ½" PVC as a pipette to draw a sample from out away from the edge and a couple feet down.

 

[tcat]

I had assumed chlorine was heavier and sank, only explanation I could think of (and I was thinking the liquidator worked on that principle). I use a turkey baster at about 15" deep for each sample. I may try another pump off sample just to see if I can duplicate it tonight. I am using a homemade feeder that dispenses 32 oz. over the 4.5 hour pump cycle. That's why I thought it odd I only got a "1" 15-30 minutes after the pump stopped, should have been at max level for that 24 hour period.

 

[mas985]

Chlorine (aqueous) is slightly heavier than water but once mixed with water it doesn't settle out (i.e. separate). The liquidator makes use of this by the way the tank is filled to minimize mixing with the water.