Okay, this isn't the equivalent of an (expensive) chiller; it won't provide huge differences between tank water temperatures and those of the ambient air. It will, however, apparently give you a few degrees of extra cooling, which may in many instances mean the difference between success and failure...or which may get you through a temporary hot spell. It costs virtually nothing to set up, and literally nothing to "operate".
I have a 70-gallon tank in my basement, set on a 30-inch-tall stand. The unfinished concrete floor is currently at 50F; the concrete wall decreases in temp as height increases, from 49F at the very bottom to about 43F at grade level. Air temperature in the basement is right at 58F and the water temp has been at 55F with all numbers very stable over about a week of measurements.
The tank itself sits about 4 inches from the wall, which measures 45F at that height. Seeing these numbers made me go "Hmmmmm..." I took some scrap pieces of styrofoam insulation, left over from insulating the outside of a couple of heated plywood tanks in an effort to reduce heat loss, and cut some long strips of a thickness that lets me jam them into the gap between the wall and the back of the tank. I created a "collar" of insulating strips that extends the length of the tank at top and bottom, and also the height of the tank at both ends; the styrofoam is simply pushed into place and held by friction, and it captures a cushion of stagnant air between the back of the tank and the concrete wall.
This cushion of air is held against the colder wall, which cools the air and in turn seems to cool the tank several degrees. The day after I fashioned this thing, the tank temperature had dropped from 55F to 53F; the next day it was down to 52F, while all the other temp measurements...floor, wall, air, etc...remained as they had been. The following day the tank water was almost-but-not-quite at 51F and it has remained at that level for the three days since. Again, all other temps have remained stable.
So the simple expedient of holding a cushion of air, chilled by direct contact with the cool concrete wall, against the back wall of the tank has given me almost 4F degrees of free cooling. Doesn't sound like much, but 4 degrees is 4 degrees; I'm happy to get it.
As the season progresses and winter moves into spring and then summer, I know from experience that the floor will only get about 2F degrees warmer than it is now. Logic dictates that at the height of summer, the wall will be at its coolest at the bottom, rather than at the top as it is now...but the wall right behind the tank will always be cooler than the ambient air, so I can't see any reason why I won't continue to enjoy a few degrees of free cooling throughout the year. I'll be watching this closely...but if my tank stays even a couple degrees cooler during the warmth of summer, it'll be a big success IMHO.
I have a 70-gallon tank in my basement, set on a 30-inch-tall stand. The unfinished concrete floor is currently at 50F; the concrete wall decreases in temp as height increases, from 49F at the very bottom to about 43F at grade level. Air temperature in the basement is right at 58F and the water temp has been at 55F with all numbers very stable over about a week of measurements.
The tank itself sits about 4 inches from the wall, which measures 45F at that height. Seeing these numbers made me go "Hmmmmm..." I took some scrap pieces of styrofoam insulation, left over from insulating the outside of a couple of heated plywood tanks in an effort to reduce heat loss, and cut some long strips of a thickness that lets me jam them into the gap between the wall and the back of the tank. I created a "collar" of insulating strips that extends the length of the tank at top and bottom, and also the height of the tank at both ends; the styrofoam is simply pushed into place and held by friction, and it captures a cushion of stagnant air between the back of the tank and the concrete wall.
This cushion of air is held against the colder wall, which cools the air and in turn seems to cool the tank several degrees. The day after I fashioned this thing, the tank temperature had dropped from 55F to 53F; the next day it was down to 52F, while all the other temp measurements...floor, wall, air, etc...remained as they had been. The following day the tank water was almost-but-not-quite at 51F and it has remained at that level for the three days since. Again, all other temps have remained stable.
So the simple expedient of holding a cushion of air, chilled by direct contact with the cool concrete wall, against the back wall of the tank has given me almost 4F degrees of free cooling. Doesn't sound like much, but 4 degrees is 4 degrees; I'm happy to get it.
As the season progresses and winter moves into spring and then summer, I know from experience that the floor will only get about 2F degrees warmer than it is now. Logic dictates that at the height of summer, the wall will be at its coolest at the bottom, rather than at the top as it is now...but the wall right behind the tank will always be cooler than the ambient air, so I can't see any reason why I won't continue to enjoy a few degrees of free cooling throughout the year. I'll be watching this closely...but if my tank stays even a couple degrees cooler during the warmth of summer, it'll be a big success IMHO.
This method will involve, at most, stuffing the styro pieces into place at the start of summer, and then removing them in the fall...or, depending upon the fish in question, just leaving them in place year round.
