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Cooling a tank--cheap?

Nov 27, 2002
I'm told that Gollum (my current octo) has no problems with warmer temperatures, which is good...thanks to my nearly sealed lids and my coral-pleasing lights, I can't bring my temp below 76 degF and it can drift up to 78. Someday poor Gollum will pass on ( :cry: ) but of course that means it'll be time for a new octo...and I hear many octos, especially the all-popular bimacs, prefer temps of 70-72 degF.

I really, really, really, really, REALLY...really...don't want to buy a chiller, which would be the most direct way to cool off 55 gallons of seawater. The price is just so exorbitant. But I really would rather not take my lighting down a notch or two...those corals would be mad at me, and Gollum certainly does have enough shady hiding places. Neither do I wish to open up the top of the tank, since it needs to discourage octo-escape. Even worse, during summer months 72 degrees is probably the low end of cost-effective apartment air-conditioning...so without cranking my air way up, I'll be trying to keep a tank at or awfully close to ambient temp!

Do I have any practical cost-effective options? My lighting is a very open design...I have considered placing a fan atop the aquarium, aimed down at the lights to circulate some air through them...any ideas?

I've been able to reduce my tank temperature by a couple of degrees by running the skimmer only at night, when the house is cooler, and making sure the water in the sump is always at the proper level. The tank stays at a warmer temperature than the room because of the lights and also because of the pumps. I'm sure there are many other good ideas for having a cooler tank, including adding a chiller.

I avoided having a sump because I felt pretty intimidated by the concept of setting up my first tank whole-hog with a sump and everything... Now I realize they don't seem so complicated or expensive...I suppose at some point I should consider upgrading the tank with one. I would certainly get some evaporative cooling that way.

Other ideas? Such as the aforementioned fan idea? There's a small, $100 peltier-effect chiller I've seen advertised, but...given it's wattage I'd be surprised if the thing could make much of a dent.

Hi rusty

heres what i did...

get on the phone to comapies that supply those drinking water fountains in offices.. I managed to get a chiller big enough for two tanks for £20 and thats a saving of nearly £500!!!!

It was a second hand chiller used for taking tap water and chilling it after it was in a simple RO unit! It was a bargain... took me a couple of phonecalls... and... if you explain what its for, they get a good laugh and they seem more interested and likely to help! :lol:

Wow, Colin! That's a fascinating idea! When I think up some more detailed questions about that I'll ask, but at the moment I have to head off to work! Silly paycheck... :P

Trickle filters also help cool water, even in when the surrounding air is warm. The taller the trickle tower the cooler the water coming out the bottom. Effiecnecy can be increased by blowing air through the trickle filter.
Not as easy to contol as a decent chiller, or an air conditioner though.

Another interesting idea...a cooling tower! I hadn't thought of that either. This is good stuff, guys... :biggrin2: I don't need a trickle filter but that doesn't mean I couldn't assemble something that's a poor filter but a good cooling tower.

Can you tell me more about this chiller, Colin? How exactly does it interface with your tank? Does it have a coil you've immersed in your tank/sump or do you actually run water through it? Was it easy to rig? Could saltwater be a problem with it? And (a big one here) I presume it's not using copper?

Colin, that is a very ingenious idea. I never thought to put the two together. It there a control unit to regulate the temperature, or is it pretty much just pre-set? The savings over a chiller are great.
Okay you two, :smile:

The chiller is cased inside a metal unit approx 18" by 12 by 12 and it has a water tank that you fill up with tap water and the unit freezes it. It also has a stainless steel coil that your aquarium water passes through which gets chilled from the ice in the water tank.

It has also got a thrermostat but that is a trial and error screw. So you need to set it up and wait until the unit switch on/off to see what temp it is set to and adjust the screw accordingly.

So using a powerhead, water is pumped through the stainless steel tube and back into the tank. My unit luckily has two stainless steel pipes so potentially could cool two tanks.

Why not go round your local pubs and bars and try to scrounge an old beer chiller... its exactly the same! Just make sure to flush the beer out properly before adding it to your tank!

These things are designed to not put anything into the water (food quality grade) and are much cheaper than buying a chiller
Wow, this just sounds better and better. It's perfectly logical that a food-grade chiller would just happen to be the same kind of design we would want. Hm. Well...all this means I must reconsider my plans of a sump design, too. It'd be easier to connect this to a sump, plus that would make it easier for me to explore the cooling tower idea.

This is great, guys! Lots of lovely and practical ideas! :biggrin2: Thanks lots.

Colin, how much "oomph" do you get out of this thing? During the summer, I bet I would be looking to knock my temp down from 80 deg. F (26.7 C) to about 70 deg. F. (21.1 C).

I bought this to keep Eledone ( a cold water species) and i need it to take water from ~68 to -50deg F.

I experimented with the chiller and it almost froze a FW bucket of water so I'm sure it will work for you fine... Just start phoning these places, give 'em the details of why you want it and that should start their brains thinking of a solution as far as a chiller is concerned.

(smacks forehead)

I have a distant family member who owns more than one bar (or "pub" for you, Colin! :P ) I will try picking his brain... maybe he has something laying around. I'll still try local outfits too, though most of them are closed over the weekend.

You mention "office water fountains." Now...are you referring to the "water cooler" with the big upended bottles of pre-filtered water that get delivered every week, or are you referring to the fixture-style water fountain, sometimes called a "bubbler" wherein you push a button/lever to get water to bubble up? The phone book lists many dealers of the former here in Springfield, but I don't know about the latter.

I have a water cooler at my fathers office. He just asked me today if I wanted to use it for the tank. It's almost like he read my mind. He said he had one lying around that he wasn't using. Now, I intend to split my tank in half, so I can have a bimac and some fish. Do you think this "chiller" will be too cold for fish? What is a good temp. for a bimac?
Bimacs are supposed to be happiest at around 70-72 F, I believe. I'm not sure how to hook one of these things up yet...hoping I can work that out once I find one! But I'm guessing that freezing your octo isn't an issue. There should be, somewhere, some built-in means for controlling the temp of the cooler. If there isn't, you should be able to compensate somehow (my mind's been chewing this over for a while now!) If you have water running through a coil immersed in the cooler's reservior, for instance, then perhaps you can physically vary the amount of the coil actually immersed. Or if it's like the design Colin mentioned, perhaps you can install a valve that would let you control the flow rate of the water.


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