I'm going to buy a used chiller for a 10 gallon cold water tank I'm planning to set up (60 degrees). I don't want to buy much more chiller than I need, but I really don't want to buy less than I need. I'm looking for some input from people with experience using small chillers on small tanks. What have you found is too small? Just right? Please let me know:

1) The brand and hp rating of your chiller.
2) The average room temp, and the temp of your tank.
3) The size of your tank, and sump.
4) How adequate you think your chiller is (not enough, too much, ...)?
5) Other factors:
.......a ) Is your tank (and sump) insulated or not?
.......b ) Is your tank glass or acrylic?
.......c ) Do you run external pumps, or submerged pumps?
.......d ) Do your lights add a significant amount of heat to your tank?

Thanks for your input. I'll start a build thread when I get the parts together and have some pictures. I'm going to keep Spanish Shawl nudibranchs in the display, and grow their food hydroid in the sump.

i think a 1/15 horsepower should be perfect. i am up for objection though.

I'm hoping to hear about peoples real world results. Have you used a 1/15th hp chiller? If so, how many degrees below room temp did it keep your tank? How big was the tank (and sump)?

Ahh i lovely species of nudibranch. Can't help you with the chiller problem though, sorry.

I have a 1/10 for my 16 g. A 1/15 would probably work, but you'd be putting a lot of strain on it, and it would be more likely to break, etc. I'd go with a 1/10 to be safe; if you're spending the money, it's not that much more just to ensure it will work out. You definitely don't need any bigger than 1/10 though.

I use a 1/13 HP CL mini Pacific Coast Imports on my insulated 5.5
I have a Aqua Clear 30, Taam nano skimmer and a Zoo Med
mini cannister filter. You can imagine the heat all the filters
produce. My temperature stays at 55 degrees with
moderate use of the chiller. 1/13 may be considered
overkill, but it gives me great control over my temperature.
I have to tell you it is much better than using 2 Ice probes
to chill my tank from the start.

I plan on using the same chiller to chill my 15 gallon
coldwater tank I am putting together this year.

H

Thanks very much for the input.

It sounds like a 1/10 would be the best way to go, and that a 1/15th would probably work. I'm a real stickler for using external pumps to keep from adding heat, and for insulating my system, so I'll bet a 1/15th would work for me.

Today, on Craigslist, I found a deal that was too good to pass up. I got a well used 1/5 HP JBJ Arctica chiller for $150. I know, great deal! I know, too big! My system will be a 10 gallon, with a 10 gallon sump. Assuming that I have 18 gallons of water in the system, and based on the BTU rating of this chiller, I calculated that it will take at least seven minutes for the chiller to lower the temp of my system one degree. That's fast, but I don't think it's so fast that it will shock my animals. The JBJ Tech says that I don't need to worry about the slow flow rate causing the water to freeze, it's just that I'll be chilling less efficiently than I could be (using a little more electricity). For $150, I can live with that.

Thanks again for your input.

good find
i'd suggest insulation for at least the back and side panels of the main tank, all of the sump's, and even around the plumbing (not only insulates but helps to avoid sweating where lower-schedule plumbing materials are used on really cool tanks)
a small fan directed at the exhaust of the chiller will allow it to run less often, saving you $ and boosting overall chilling capacity
also, keep it clean (esp. air vents)... you'll be surprised what a difference that can make
even though you will impulsively want to hide the unit, it's way better to install it somewhere in the open for good heat exchange, as well as monitoring & maintenance