Cheap tips to keep res temps stable

I have been searching around and I have only really found expensive ways to cool the res temps.. I'm hoping we can get some tips from Hydro Growers to keep res temps not only lower but stable also. For example if you put a frozen jug in your res- how big is the jug? How big is the res? What is the before temp and the after temp? How long does this solution hold the correct temp?......

Correct temps are crucial for preventing root rot, preventing algae growth, and ensuring higher oxygen levels in the water... Thanks to all who can contribute.

I will start out with an obvious one. Wrap your res with Mylar. This will stabalize temps a little. If u combine this with adding a frozen jug of water daily you will be close to where u want to be. The jug size depends on your res size, and the amount of jugs you have to add depends on your room temps. I have found that adding a quart or half liter per day to a 3gal res seems to work for me......After further review this doesn't work well at all. My res temps crept up to 80+deg today.

I have another way of cooling the res for cheap but it may take a little work ideas from Delta9nxs on a different forum. If you use Rev Osmosis the waste water is ussually 55*, so if you can figure out a way to run that water thru a coil in the res u can take off a few degrees right there, and if it runs too fast yoiu can . If you want to really get technical the average household runs 200+ gallons a day(according to this guy). All the cold water from the entire home could be run thru a coil in your res first. This could be as easy as one hose hooked up to the proper coil, not copper!!!, and then a hose back to the water hookups if your grow room is in a basement, otherwise it could prove very difficult. These ways listed are only going to knock 10*max out of your res at their most effective point, but ussually I see people only need 5degrees or so.
Another effective way to reduce res temps 5-7* is simply blowing cool air into the res form an open hole in the top with a few computer fans. This way is proven to reduce temps of a 50gal res 5-7*f
Yet another way I saw was to use a coolant module from a window AC This guy just very carefully unbent the copper module away from the unit after undoing a few bolts and removing any casing that covered the module. He then put the copper module right in his res and asid it cooled a 50gal res from 80-90-a solid 55. After he put the thermostat that is also hooked up to the ac into the res along with the cooling module the res stays at a steady 65*. If this copper breaks it will cause the release of a shit ton of freon so be carefull as hell when unbending and handling the cooling module. Instead of putting the copper right into the res I would put it into a tupperware container sealing the copper completely from entering the water. Before sealing the tupperware off, with the module inside of it and the remaining area filled with water to conduct the cold coil to the res water.
More info on these can be found by searching this these posts
Homemade chiller for nutrient? An idea - The Garden's Cure