Today I tested a cooler that I made close to the mother of fermentation, available online. It worked well - I put three 1/2 gal milk jugs with ice in the evening, and filled a 6.5 gal carboy with the tap water at about 75 degrees. The fan kicked in immediately, and worked all night. In the morning the water was 57 degrees. (Well, actually I use centigrade, so it was from 24 to 14.) Then the fan started turning on and off. The only bad thing is that the milk jugs developed cracks and leaked, so I'll probably go with the blue elements.
I did make a few changes in my design. First, I did not want a removable top. Instead of hinges I use metal square tubes and bolts. I also added a 12v light and a viewing hole in the front door, so I can see the bubbles without opening the door Here are some pictures:
I did make a few changes in my design. First, I did not want a removable top. Instead of hinges I use metal square tubes and bolts. I also added a 12v light and a viewing hole in the front door, so I can see the bubbles without opening the door Here are some pictures: