Homemade chiller

[Natty Bumppo]

We keep an aquarium in our shop at work, and recently upgraded from a 20 gallon to a 55 gallon tank. Our shop is not air-conditioned and during the summer, temperatures inside can get into the 90's. We began our tank last September as temperatures cooled. I knew we would need some way to cool the tank by this summer, so last fall during a budget planning meeting, I requested $5-600 for a chiller. I was told no.
I knew we had to do something, so we jury rigged a cooler using a small, submersible pump, some vinyl tubing, a copper coil, and an old refrigerator. Tank water is pumped through the tubing, into a copper coil that rests in a chilled water bath inside the refrigerator. The water is cooled and returns via discharge tubing back into the tank.
We just finished it today. As we monitor temperatures we'll play with the frig temp setting and length of time the pump runs (it's plugged into a timer power strip).
By way of explanation, I should add we went from a gravel bottom in our 20 gallon tank to a sand bottom in the 55. I got a bucket of sand from a large sand pile pushed up after the '93 flood in a nearby river bottom area. A mistake. Should've rinsed the sand. Water is still fairly cloudy. We went from an HOB filter to a Fluval 306. I've rinsed out the sponge filters a couple times as we wait for things to clarify and have ordered some finer, "polishing" filters. We had a similar issue with the gravel used in our last tank, harvested from our local stream.
We angled the discharge tube so it would flow in a more horizontal fashion rather than jet water down into the sand substrate and stir things up more. As an unexpected bonus, our local creek fish seem to really like the added water movement in the tank.
I should also add the OSB (oriented strand board) lid on the right side of the tank is only temporary. The 24X12 hood from our 20 gallon tank covers half this tank. I've ordered another lighted hood for the rest. Until it arrives, we're using the wooden top.

 

[Fish Tank Travis]

What fish are you keeping in the tank?

 

[Natty Bumppo]

What fish are you keeping in the tank?

We have a channel cat, couple madtoms, pair of red shiners (in their breeding colors right now), some carmine shiners, a few small longear sunfish, some central stonerollers and creek chub. On occasion we throw some mosquito fish in. They don't seem to last long. They're small and I suspect the channel cat makes short work of them after dark.
We've had issues w/ suckers, both redhorse and northern hogsuckers. Neat looking fish, but we can't seem to keep them more than 4-6 months. Since we've gone from gravel to sand, I don't think the suckers and darters would like it as well. But we do have more "current" in the tank now.

 

[Natty Bumppo]

By way of an update: After a few days, the chiller is keeping the tank in the mid to upper 70's right now, with outside and shop temperatures getting to 90 in the afternoon. I had been concerned when we plugged it in, it might make things too cold. That has not been the case.

On Friday, our water bath in the frig was about 70 F while the air temp in the frig was 48. I had figured the water bath would chill our tank water in the coil. Hadn't really thought about our tank water significantly warming the solution (actually a water and anti-freeze mix) in the frig. Probably no more than a gallon in the tray the coil sits in. We can fit a 5-gallon bucket in the frig and will switch over to that on Monday, starting w/ cool well water. We can also turn the frig thermostat to a cooler setting.

Right now the pump is plugged into the same timed outlet the light is plugged in to. So it runs from about 8:00 a.m. until 3:30 p.m. I've ordered a separate timer power strip for the pump. We can play with when and for how long the pump runs independent of the light. Letting the pump rest on occasion should give the solution in the water bath time to "re-cool". Ideally, during the heat of summer, I'd like to see our tank stay around 75, the current temp of the creek we get most of our fish from. A little cooler is OK too.

 

[JK47]

By way of an update: After a few days, the chiller is keeping the tank in the mid to upper 70's right now, with outside and shop temperatures getting to 90 in the afternoon. I had been concerned when we plugged it in, it might make things too cold. That has not been the case.

On Friday, our water bath in the frig was about 70 F while the air temp in the frig was 48. I had figured the water bath would chill our tank water in the coil. Hadn't really thought about our tank water significantly warming the solution (actually a water and anti-freeze mix) in the frig. Probably no more than a gallon in the tray the coil sits in. We can fit a 5-gallon bucket in the frig and will switch over to that on Monday, starting w/ cool well water. We can also turn the frig thermostat to a cooler setting.

Right now the pump is plugged into the same timed outlet the light is plugged in to. So it runs from about 8:00 a.m. until 3:30 p.m. I've ordered a separate timer power strip for the pump. We can play with when and for how long the pump runs independent of the light. Letting the pump rest on occasion should give the solution in the water bath time to "re-cool". Ideally, during the heat of summer, I'd like to see our tank stay around 75, the current temp of the creek we get most of our fish from. A little cooler is OK too.

Brilliant idea/approach. One thing you may consider is a temp controller for heaters. In your case run it opposite. On at high temp, off at low temp. Then you won't have the mess with timers.

 

[paulW]

The copper tubing might cause problems over time (adding copper to your tank). You may want to replace it with plastic tubing.. But a great idea, thanks for sharing.

 

[Fish Tank Travis]

Honestly, I think your best option here is to go with a continuous cold water drip. Basically, use a carbon filter to remove chlorine and then let it continuously run into the tank and then have an overflow into a drain to allow the flow out. This will keep the water at whatever temp your ground water is, which should definitely be 75 or below.

Btw, I'm not sure if anybody has told you this, but you are WAY overstocked. The channel cat should be in a minimum of at least 300 gallon tank, but probably should still be in a larger one. In addition, the sunfish should be in at least a 125, and that's if you just have a small group of them by themselves. I'm not trying to discourage you, but you should probably look at some more appropriate options for that tank. Have you thought about making it a tropical tank and getting some smaller cichlids, and maybe a few pictus catfish? You can get all of those at a pretty cheap price and they will be very entertaining.

 

[Natty Bumppo]

Honestly, I think your best option here is to go with a continuous cold water drip. Basically, use a carbon filter to remove chlorine and then let it continuously run into the tank and then have an overflow into a drain to allow the flow out. This will keep the water at whatever temp your ground water is, which should definitely be 75 or below.

Btw, I'm not sure if anybody has told you this, but you are WAY overstocked. The channel cat should be in a minimum of at least 300 gallon tank, but probably should still be in a larger one. In addition, the sunfish should be in at least a 125 . . . .

I appreciate all the input. I wasn't familiar with a cold water drip system; but, keep in mind, the tank is in a shop (as in work benches and equipment, not a retail shop) with no indoor plumbing. Our water source is an exterior well and hydrant. And we usually do water changes with water from our local creek where the fish came from. This is due in part to it being softer so we don't have as much rust and lime accumulation on everything.

At present we have about 13 fish in a 55 gallon tank. The channel cat is the largest, at about 6 inches long. The tank is 48" long. When he gets too big for the tank, we'll make other arrangements for him. We did this with the bass in our 30 gallon office tank. When he got to be about 7", we gave him to our nearby nature center and he now calls their 600-800 gallon tank home. The long-ear sunfish is about 3" long and the green sunfish about 2". I'm fairly new to the aquarium game, but I'm not convinced we're overstocked.

Tropical fish are pretty, but we're in the conservation business and prefer to have native fish in our tank. In addition, the tank water temperature typically gets into the mid to upper 50's in the winter. The shop is heated, but when we're not there, we usually turn the thermostat down to its lowest setting. For native, midwestern fish, this is no big deal.

 

[Natty Bumppo]

I should add, regarding the 13 fish in the tank and what I outlined earlier as what we had in the tank: there's been a small amount of attrition in the last month. I suspected the channel cat was behind it. The other day I noticed he had a very swollen belly that seemed to confirm it. I believe most of what's left is a little large for him to handle.