Help selecting a Ciller

dkdiskin · Jun 16, 2022

Hello,

I have a 900 gallon fish only aquarium.
I live in Michigan.
There are a few weeks in the summer when the temperature of the tank gets to 80 degrees.
The aquarium is in an insulated room with fans and an air conditioner.
I need a chiller that will lower the temperature of the tank 5 degrees.
I'd appreciate your opinions on the size and make of chiller .

Thank you

Uriken · Jun 16, 2022

I'm not sure if that is supposed to be 90 gallons or you meant to type 900 gallons. I live in Northeast Ohio and right now we are on day 2 of 95 degrees but tomorrow back to 78 degrees. I try and use the wall AC unit to cool the room on days when I know the temp is going up. Chiller costs are nuts and building a DIY unit really isn't practical for an "occasional" need. With 900 gallons I would say you would have to go with an Industrial type chiller used for large equipment that are available. But again, not cheap at all. The good quality larger 1hp units you see from the various Saltwater Dealers are going to get into the 4 digit cost range easy and Id honestly still question if it could keep up with 900 gallons. I think as long as you can keep the temp from going up prior to hot days it may help hold it there. Once the saltwater gets on the hotter side its much harder to pull it back down. Its a tough one when you only have a few hot days in the summer.

Eagle_Steve · Jun 16, 2022

dkdiskin said:
Hello,

I have a 900 gallon fish only aquarium.
I live in Michigan.
There are a few weeks in the summer when the temperature of the tank gets to 80 degrees.
The aquarium is in an insulated room with fans and an air conditioner.
I need a chiller that will lower the temperature of the tank 5 degrees.
I'd appreciate your opinions on the size and make of chiller .

Thank you

Since this is only for a short period of time, have you tried some fans blowing over the top of the tank or the sump? I can get 5-6 degrees reduction in southern TN in the summer with no issues doing this. And this is in a not very well insulated min barn lol. My evap goes up when doing this, but long term, the cost has not really been that much. Especially with that water volume, the temp change takes longer. This means once you get it to temp, if setup correctly and the fans are on a ranco or inkbord, you should be able to keep it within 1 degree of your target with no issue.

If I had to get a chiller for that size tank, depnding on how long it takes to get to that temp, you are going to need at least 1hp or more to control the temp. It may be possible to use a smaller size chiller, but that all depends on how long it takes to get from normal temp to way to out of range temp. From there, you can do some long math to figure out how many btu is needed to cool it down.

In short, I would suggest trying some box fans blowing over the top of the tank for a day or 2 before I make a 2-3k investment on a chiller for a 900 gallon tank that the chiller would only be in use for a short time during the year.

In addition, you may need to look at the equipment in the tank and what is actually generating heat. There may be some options to change those to less heat generating items and problem solved that way for less money.