Diy chiller idea

[Der ABT]

So my 7g qt tank has been getting too hot, the room it's in is small and we have had some ac issues and are waiting on a replacement core....and it's can get warm in there.

I keep it covered most of the time so there isn't too much humidity in the room but also put a fan and leave it open on hot days for evap cooling

 

I was thinking about using some 1/8th tubing and either coiling it in the tank and having rodi from my 50g holding drum run thru the line....this would put the pumps heat in the 50g vs 7g

 

or running a pump with water from the qt into the Rodi as the holding tank is usually a bit cooler....but then I figured the pump heat would make this a bad choice

 

Or

I have a mini fridge up there and was thinking about drilling a hole and running a closed loop in there with a small 1 gal container with a pump etc

 

Thinking this could be a good emergency cooking solution I could set up on a controller. ....aka if temp hits 83....pump turns on and water flows from fridge or thru fridge etc.

 

Trying to figure out a cheap emergency cooling back up so I don't loose any more corals.

 

Any thoughts?

[sethsolomon]

look into an ice probe.  Much more energy efficient option. I think Marine Scene has one on clearance for like $60. 

[Origami]

I think that the ice probe is a single-stage Pelletier cooler. I'm guessing that it has an efficiency of about 25% based on the technology alone.  The Novatec ice probe manual claims that one probe can drop the temperature of a 10 gallon aquarium by 6-8 degrees F, and a 20 gallon by 3-4, and a 40 by 1-2. Of course, your mileage may vary. If the room itself is hot, then you may find that an iceprobe is not going to give you too much relief because it's trying to dump the heat into the room, which is already hot. Think of it as a device that's trying to move (push) heat. If the room is hotter than the tank, then it's pushing uphill. If it's lower, then it's pushing downhill. It can only do so much work, so pushing uphill is not going to move very much heat very fast. And, given conduction of heat into the tank from the surrounding room, it may be a losing battle. If the heat is coming from other sources (pumps, lights, etc.) and the room itself is cool, then an ice probe may work just fine. Gas-compression coolers are more efficient and more capable for larger applications. This would be something like a JBJ Artica or other standard chiller. If bought used, you can recoup most of the purchase cost back in resale with operating cost being the primary expense (as long as maintenance does not become an issue). (But a full-up chiller on a 7 gallon tank seems like overkill at first. It would certainly work, though.) 

 

So, the first question would really be: How hot is the room? If it gets to 90, then you may have problems with an iceprobe trying to dump heat into an already hot room. If it's only 85 degrees, then it may work. 

 

Now, to your ideas: Plastic tubing is a poor conductor of heat. For example, the thermal conductivity of low density polyethylene (LDPE), for example, is over 1,000 times poorer than pure copper of the same thickness. To make up for that shortcoming, you'd need to use thinner tubing or increase the surface area (i.e. longer tubing) or increase the temperature differential (that is, dump the heat into an even cooler sink of water, for example). There's a lot that would go into calculating if this could be made efficient (and I'm not sure that it really could) unless you were taking advantage of a pre-existing place to sink the heat (into the ground, into an existing cool water reservoir, etc.). To mitigate adding heat from a pump, you'd could use an external pump (peristaltic for example), but that's an added expense. The mini-fridge idea might work, but you'd want as much tubing in there as possible and the ability to adjust the flow rate through the tubing to find the least amount of time that the pump needed to be on to get the job done. You might also want the fridge to do double-duty, like keeping some drinks cold for you, since it would be a dedicated expense otherwise. 

 

Is there any chance of putting a larger saltwater reservoir in a cooler part of the building and increasing the system volume?

[sethsolomon]

Might be another option:  http://www.fish-street.com/aquadg_dc_mini_chiller  assuming you don't mind doing temp conversions.

[Origami]

^^ Interesting thing from Fish-Street.

 

Here's another, larger thermoelectric cooler with 10+ degrees of pull-down. 

 

Another option to consider, if you want to build something, is an evaporative cooler. Pump water onto a surface, expose it to airflow to increase evaporation and cool the water in the process, then return the water to the tank. It'll increase your ATO needs, of course. It also tends to work better in low humidity conditions, so if your AC's not working and the humidity climbs in the room, it'll be less efficient. 

[Der ABT]

Was trying to do it cheap with what I have on hand. Again more looking for an emergency back up that my aciii could turn on if needed

 

Already have the fridge and it holds beverages and had a small freezer section for frozen Fish food.and is next to the main tank so not heating the qt room.

 

Was thinking of putting a 1g jug inside the fridge with water and a bilge pump much like the cool suit we use in the race car or just a maxijet etc. So it wold be pretty cold water and I have a bunch of tubing etc sitting around I could coil in the qt.

 

 

I'll have to get some temps in the room...it's a half room with the roof right there at a 45angle.

 

Thanks for the link seth thag may be an option if once the ac is fixed the room stays hot...or as an emergency backup.

 

Guess it may be tougher than I thought to do cheaply.....but that nano chI'll er isn't too horrible......I mean if I have a few hundred bucks worth of frags going thru qt for a couple weeks, 70 is worth the safety

 

Thanks for the thoughts and usual Tom plethora of information and things to think about

 

My coolsuit gave me the idea...here is a link for 5hose who don't know what they are.....make a 90min enduro racing much more tolerable in a nomex suit and hot car.

http://www.fastraceproducts.com/cooling/driver-cool-suit-systems/f.a.s.t.-cool-suit-system-no-air-no-shirt.html

[Origami]

Just use lots of tubing and, if possible, try to keep as much of it exposed to the water that you're trying to chill. That is, coil it kind of loosely.

[Origami]

Evan, have you tried a fan?

[sethsolomon]

Be careful if you decide to drill the fridge.  I strongly recommend finding schematics to see where the Freon lines are at before you drill.  I have popped 2 mini fridges drilling before getting the drill right.