Delay between shocking and measuring baseline

[snewo]

I seem to have read somewhere that you should wait about a half hour after adding the liquid chlorine before you take a baseline measurement. That doesn't work for me at all. I suspected that I might have some algae in my pool, so it was time to give her a shock. Using the pool calculator I entered the amount that should get me to a FC of 24 (my cya is 60). Here is what I saw:

.5 hours after adding bleach: FC = 22.5
1.5 hours after adding bleach: FC = 25.5
2.5 hours after adding bleach: FC = 26.5

Yes, I had my SWG turned off (0%). No, I do not suspect operator error on performing the test. Here's what I think.

I think the number of gallons that I've been using is slightly off. I'll have to work on that one. I always add chlorine by a return and I always measure from the same spot, so maybe the pool's circulation takes a little while to fully mix the liquid chlorine.

Does anyone else see around a 2.5 - 3 hours wait in order to get accurate test results? It kinda makes doing the whole overnight loss test a time sensitive event for me. Just curious if some others have seen the same thing. FWIW, my filter was ready to be backwashed and I did so after the 2.5 hours, so perhaps the full amount of water was not circulating.

 

[waste]

I know others say to add the bleach in one spot in front of an active return, but I've always walked it around the perimeter with the pool running. I feel that doing it this way will both get the chlorine into all the water more quickly, and also, have the full effect more quickly

Any chance you will repeat this experiment and see what the difference is in distribution/ cl rise?

 

[snewo]

Perhaps the next time I add that much chlorine I'll look at it. Right now I'm running low on R-0871 so I'm picking and choosing my test points. Time to go order refills....

 

[Buggsw]

I do what Dave does. I may not go around the entire perimeter unless I am adding quite a lot as could be if you have to raise shock level up very high, besides, I use 12% so the quantity is smaller than would be at 6%. I also don't have a normal return. My return is the 10 in ground pop ups. I know my pool gets mixed quite well in a short amount of time.

 

[snewo]

The same thing happened again last night.

9:45pm I added enough chlorine to get me up to FC 24
10:15pm I measured FC 22.5
1:05am I measured FC 25

I'm going to take your advice and spread the chlorine around a bit next time. I've always been adding in the deepend by a return, but tonight I'll add all around and see if it makes a difference. That is, of course, if it ever stops raining.