Take a look at a few bottles with a bright light behind them. Might have an infection in some of the bottles. You'll see the cloudy before you open them. I'm dealing with this on a nut brown right now...
Hope that helps. Or moreover hope that's not the issue and it is something less...
Yooper is very correct in his statement.
It's not as much about surface area as it is difference of temps and quantity of volumes. Try the ice bath to 100 and mix with 2.5g freezer water method and you'll be amazed. Sometimes I would fall to mid fifties in mid winter in Florida using this...
Just finished a batch. Hit my OG at 1.058. Pitch temp a little warm at 83F, but this is Florida and I need to sleep now.
I used 1098 British and think it will be great.
My first ALL AG with no supplemental DME. Surprised my little cooler held the temps (well laid out BTW).