This is what I do usually to reduce the water temperature:
1. Get a fan to blow across the top of the water.
2. Get too hot get ice cubes and put them in a bag and float them in the tank.
3. Run your tank when at night by having the lights on at 4-5PM till 11PM. This is good too cause you are not using electricity during peak hours.
4. Get a chiller...
The fan actually works pretty well for my reef tank I have a fan blowing across it almost 24/7 and have the lights come on at night and my temperature didn't get too hot. Just watch out for the evaporation rate also I had to refill about 1/2 a gallon a day in a 20 gallon tank in the summer.
You can do something like DIY fan with small computer fan and that could bring down 1-3 degree. You can also buy aquarium fan. I killed about 3-4 shrimps other day because I didn't turn on my fan and tempture was about 78-80... Now my tank is 74-76 around there.
We've had a few oddball hot flashes in my neck of the woods. I lowered the blinds and floated ice cubes in a bag on the super hot days and watched my water temp. It never got above 82. Typically I have it set to 79.
Thanks for the frozen water bottle idea, that one sounds like a great solution.
Here in AZ everyone has an air conditioner (and if you don't you buy one before spending money on shrimp) so you just have to keep it cool enough. I would recommend trying the fan idea first. It can lower the water temp by quite a bit depending on the humidity. Its also the cheapest method and doesn't involve replace bottles of ice.
Depending on your setup, you can do water slow, frequent water changes. All of my shrimp tanks are on a system where the tap water goes through a house filter, then into two 44gal Rubbermaid garbage cans. The water in the cans has large airstones and heaters (for the winter months). Early this summer we had a surprise 95+ weekend and our A/C died the day before! Even though the shrimp were in the basement, all the tanks jumped to 83 degrees. I basically drained the stored water, let the cold tap water refill (~73 degrees off the street) and let the impurities and chlorine filter out. By the end of the last day of the heat wave I was able to keep the temps to around 76 degrees. The next day the A/C was fixed. In the end I only lost 1 berried CRS (of course) and a berried Blue Pearl.. the rest of masses of shrimp were spared.
Obviously this isn't a solution for most, but perhaps can give some other options for all of you living in the heat.
I was curious about your use of the airstones in the stored water. I also use the 44G container method (with heater), but haven't used any aeration with this water. Are there additional benefits to this?
Well, none that I can prove by research haha. I will say that adding an air stone (mine is a 3" ball) it likely creates circulation so the water heats faster and more evenly. If I take too long to replace the carbon insert in the house water filter, the aeration will help get rid of chlorine and/or other gases that may be present.
The downside is that it will also assimilate the water to room temperature quicker too, which is why I turned it down when I was doing the long water changes to lower the temperatures.
This is all in "theory" though... I have not taken the time to measure anything other than temperatures. If someone can see a flaw that I've overlooked please help me before I am the demise to hundreds of shrimp haha.