Chiller setup questions

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mad1ben2

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I'm building a diy chiller out of a small dorm frig (thermostat set on min temp so no chance water will freeze). I would have put this in the diy forum but my questions aren't really about how to build it...

The details (to help answer my questions) :
- approx 200 ft 1/2" PE tubing (irrigation stuff by Raindrip) will be put in mini frig (likely a tight fit). Holds roughly 1.5 gallons of water
- using spare mag drive 7, externally connected.
- 20 gal JBJ AIO display tank in my garage, current temp is 79-80 (expecting it will get hot in summer months but honestly have never checked temp during hottest times, I'm in NC)
- plan to use a dual temp controller that has a plug for heater and a plug for chiller. Obviously once temps are set the heater turns on when temp drops below threshold and chiller (the mag drive pump) turns on when temp rises above threshold (these are 2 separate temp thresholds).

Questions/concerns:
1. Don't know when I'll need the chiller but don't want to wait until then so want it set up and ready to go before I need it. That means 1.5 gallons of water will just be sitting in the "chiller" at very low temp.
Q: If it's there for a long time (weeks?) are there concerns with it getting stale or stagnate?

2. If I set chiller to come on at say 83 deg I doubt it will take much of that really cold water to bring temp back down to normal. My AIO JBJ 20g cube has 3 sections (overflow, media, return). I plan to pull water out from the overflow section and return chilled water to media section - putting controller temp probe in overflow section.
Q: are those the right sections to pull and return to? Right place for controller probe?

3. Since water sitting in chiller will likely be very cold, I can't imagine when the pump turns on that it will take much water to cool down to the threshold (which will turn off chiller pump).
Q: will I cool down the DT water too quickly before the water overflowing to 1st filter section will detect the lowered temp and turn off the chiller pump?
Q: is it best to run the pump fully open (steady flow out of 1/2" tubing) or use valve on pump output to throttle back to a much smaller flow?
Q: if smaller flow is better, would it make more sense to have less tubing in chiller? Maybe 100' instead of 200'?

Am I missing something? Am I over-thinking this? I don't think the chiller will need to run much at all, so when it does kick on the water will be quite cold in comparison to the tank water.

I know a garage is not the best environment for a tank, but that's where it is and I'd like to find a way to keep the temp steady. It's only been set up a couple months... I run 2 oversized heaters and they had no problem keeping temp steady through winter... I'm trying to think ahead and be prepared for when garage temps get higher than 80... and I happen to have a spare mini frig doing nothing...

Thx in advance for any help...
 
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Snoopy 67

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Yes the water WILL GO BAD. I had a pipe inside the tank go bad with stagnant water.
Mini Fridge is a crap shoot but a mag pump puts out heat when running.
Better off with the right sized chiller that will cycle when needed & the water keeps flowing.
 

Shanet

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Q: If it's there for a long time (weeks?) are there concerns with it getting stale or stagnate?
I have a remote chiller (out in the garage). I have a timer on the pump so that every day regardless of need, the pump will cycle for 1 minute so the water gets refreshed.
Q: are those the right sections to pull and return to? Right place for controller probe?
Yes, that should work.
Q: is it best to run the pump fully open (steady flow out of 1/2" tubing) or use valve on pump output to throttle back to a much smaller flow?
Q: if smaller flow is better, would it make more sense to have less tubing in chiller? Maybe 100' instead of 200'?
Slower is better, the amount of hose will depend on how fast the water is cooled in it and the capacity for cooling the fridge has. I would stick with as much hose you can fit in the fridge and fed slowly into the tank.

A proper chiller is easier and fit for purpose if you can afford one.
 

DrMMI

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I believe each chiller has a preferred flow rate, similar to a uv. I have my temp probe in my overflow and the chiller plumbing from the start of my sump and dumping out near my return pump. The pump for the chiller runs 24/7 so the water is never stagnant. The chiller itself will turn on or off depending on the tank temp.
 

Rjramos

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As stated chillers can maintain a 1 degree differential, so there are small temp changes as the chiller cycles on and off. The water also needs to be constantly flowing to through to achieve this. In a 20 gal, setting it turn on at 82 and off at 78 would be a seesaw in temp fluctuations and stress your corals and fish. And yes this change would happen quick in a 20 gal. The equivalent of someone throwing a pot of cold water on you in the hot shower, lol.
 
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mad1ben2

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Many thanks to all for taking the time to respond... a lot of great points made and I'm thinking I need to rethink the whole plan from square one...
 

KStatefan

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Doubt a mini fridge chiller will do much. They don’t have much in the way of BTUs.

There used to be a good article written up on the some where.
found it.

 
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