hi guys thanks for tips, here's a couple tips i learned by research:
1. don't put ice cubes or anything frozen b/c it will be a dramatic temperature decrease. just imagine putting ice in a warm cup and how quick the water temp changes. this will stress your fish.
2. turn your heater UP in the summer. b/c mine was set at 82 and it hit 90 which is a 8 degree change. i now set mines at 84, so next time if it hits 90 it will be a 6 degree change in temp which will stress the fish less. you can even set it to 85 or 86 so that the temp changes won't be so dramatic.
1. don't put ice cubes or anything frozen b/c it will be a dramatic temperature decrease. just imagine putting ice in a warm cup and how quick the water temp changes. this will stress your fish.
2. turn your heater UP in the summer. b/c mine was set at 82 and it hit 90 which is a 8 degree change. i now set mines at 84, so next time if it hits 90 it will be a 6 degree change in temp which will stress the fish less. you can even set it to 85 or 86 so that the temp changes won't be so dramatic.
More aeration should do the job. Last year, I tried the frozen water bottle method - pain on the butt! 
The tank temp only went down from 90 to 88! 
This year, I run my systems with a good air pump that can run up to 60 air stones! I put 6-8 air stones in each tank - Tank temp 84-86 
BTW, just unplug the heaters. For some reason, heater keeps turn on and off, even tank temp is higher than set temp. Don't count on those set temp. 
Two, 2 liter bottles of ice in a 100gallons of water will change nothing drastically, it'll only drop the temp a couple of degrees at best.
the idea would be to keep the water from excessive heating not add too it.
