Build your own Ice Probe?

[Anonymous]

So my tank (20 gal with 9 gal sump) has been running at 84-86 degrees lately. We finally got an AC, and it's helping. But I could use another couple of degrees, so we don't have to run the AC when we're not here.

(I just checked, and it's at 82. AC is running, and there's a fan on the sump- Literally lying on the top of the sump.)

So I need a little more help. But paying $200 for an ice probe and a controller is not gonna happen. For the same amount of cash I can get a BIGGER AC unit and not have to worry about it.

Now, I know that peltiers are not that efficent. But do you think building one would be worth it?

I've priced it out, and the parts would be about $50 for the cooler.

130w Peltier $10
12v 6amp PS $30
Piece of Titanium Tubing, ~$10
12v fan $10

I have an old bulkead, tools, wire, ect.

My only qustion would be how to attach the tubing to the peltier. One thought I had was to get a larger piece of tubing, and get a couple of smaller peltiers and stick them around the sides. I'd get a 1.5" or so piece and square off one end, so the peltiers would have a flat spot to adhere to. Then I just have to seal the inside of the tube. (anyone got any Ti welding rods?)

The other option is using aluminum, and making a 'cup' Taking a tube and welding a plate on the bottom for the peltier. Then I coat the aluminum with epoxy/resin.

The hot side of the junction is easy, heatsinc and fan. Although if I go with the many smaller peltiers, it may be dificult to get a fan to pull air across all 4 sincs.

So, what do you guys think?

B

 

[RacinRabit]

Have you considered 3/4 filling a water bottle (adhesive and labels removed), freezing it, and then letting the bottle float in the sump as a cooling medium? Being in the bottle, the water will not mix with the saline water in the sump, yet it will help with the warm temperatures in a cost-effective way. :idea: You can monitor temperatures to see how many bottles will be ideal and how long they are effective for. Obviously not terribly scientific, but is a lot cheaper!

 

[Anonymous]

Titanium is terribly difficult to work with, even if you get the soft stuff that is safe for the reef (instead of one of the alloys).

 

[Anonymous]

I've got 4 bottles that I rotate. My sump isn't big enough for anything but a 20 oz. So it will last about an hour. THen the temp creeps back up. Changing bottles every hour is a pain in the arse. Also, the temp swings more then, and that's not good for the tank.

I don't mind spending the money. I just don't have $200 for the ice probe. And from the specs listed, a 20 gallon would only get a 1-2 degree drop. I'm pretty sure I can get more than that by using titanium as a heat exchanger, and running the peliters at higher amps.

I'm looking at July when it's really hot, and the AC is just not doing it.

B

 

[Anonymous]

How about used chiller/iceprobe?

 

[sediener]

Have you vented your hood and added a fan? That can make a difference and only costs 10$ or so....

What type of lighting do you have?

- steve

 

[Anonymous]

I have a 150 PFO fixture in my hood. There's also a PC fan, and the canopy is open-backed.

I've had 2 clip on fans running, one over the sump, and one blowing across the top of the tank.

The tank is still 82 degrees.

I doubt I could find a used Ice probe and controller for under $150. I can build a similar one for under $75.

The only piece of large tubing I could find was 2 feet of 2" tubing. Too much cost. So I'll most likely go wiith aluminum. I'd rather use copper, but I won't take the chance on the coating failing after time.

Aluminium is so much cheaper, I can make a few different elements.

Looks like it's time for Ebay!

B

 

[Anonymous]

So I found a relay, 90ohm 12v, 8 amp.

Now, does the relay trip when you go over 90ohms on the whole circuit? If so, I think I can build a controller for the chiller element for about $5.

So who can tell me about the relay. I can't find a decisive answer on line.

Thanks
B

 

[gatorracer]

They make ice packs for baby food and bottles that are sweet. You freeze it over night and that thing stays cold forever. We travled about 8 hours one day with it and it was still rock hard and cold when we unloaded all of our crap. I have used on before when one of my heaters got out of wack and got my temp in my 100 gallon up to about 87. The pack was still cool to the touch after sitting in the tank all night. It dropped it about 7 degrees when all was said and done.

Just my experience though

 

[Anonymous]

>...So I found a relay, 90ohm 12v, 8 amp.

Not specific enough. The relay will trip if you supply 12 V to it, but again, not specific in the spec. It can handle 8A of current at 12V, but again, not very specific. The coil on the relay is 90 ohm, that's how I read it. You need to get better info before you hook it up and fire it, Bingo.

 

[SnowManSnow]

You said you have a fan on ur sump.. is it blowing DOWN or up? If it isn't try blowing it DOWN onto the water to aid in evaporation (cooling).

Just a thought.

B.

 

[Anonymous]

You said you have a fan on ur sump.. is it blowing DOWN or up? If it isn't try blowing it DOWN onto the water to aid in evaporation (cooling).

Just a thought.

B.

there's one in the canopy blowing down on the water, and there's another lying on top of my sump blowing down as well. Still sitting at 82.

http://www.allelectronics.com/cgi-bin/category.cgi?category=500700&item=RLY-443&type=store
is the relay.

 

[Anonymous]

Here's the circuit. I'm just looking for what values to put in for the Thermistor and the pot.

12v , thermistor, relay, and potentiometer. When the Thermistor gets hot, the resistance decreases (letting more voltage through.) tripping the relay. the pot is so you can adjust the trip point.

The whole circuit should be under $5 in parts.

And explaining the thing just turned on the lightbulb in my head. Duh. It's the votage I'm looking for. The ohmage doesn't really matter, other than total on the circuit.

B

 

[Anonymous]

I have a feeling that the relay going to trip at 78F this hour, and tomorrow morning, it will need to be 95F for it to trip....

 

[sediener]

There was a DIY on RC where someone took a digital house thermostat and turned it into a temp controller... cost about 30-40$ or so for the job. You could always go for the ranco controller and have something thats a little easier.

- steve

 

[Anonymous]

I have a feeling that the relay going to trip at 78F this hour, and tomorrow morning, it will need to be 95F for it to trip....

Why is that? If the components are sealed, humidity/time shouldn't change temp.

Can you explain?

thanks
B

 

[elaw62]

Don't build or buy anything that comes in contact with your water out of aluminum. salt water has quite a corrosive action on it. titanium or possibly 316ss a much better choice.

 

[Anonymous]

Sorry, Bingo. Missed the thread until elaw62 dig it up. The reason I said it will trip the relay at very different temperature is due to the circuit not for precise application. To use the thermistor correctly, you need to use a version of the Wheaton bridges, or some other components that can amplify the difference in resistance due to temperature.

 

[Anonymous]

It's been put on the back burner. The roommate bought an Inside ac. So the tanks a nice 82 all the time.

And I can't find the piece of aluminum I want for the price I want. I also haven't drawn up what I want. (1 1/2" solid square rod tooled down to have threads on one end. Then I'd epxy it and thread it in a 1" hole. and put the nut on it.)

but since the roommate bought an ac, the probe will have to wait. (I've got friends I grew up with who run CNC mills, No problem for them to cut the piece)

I'll look up the wheaton bridge, and see how I can put it in.

I also found really small PS's that are 12v 8.6 amps, but they have a minimum load of 400ma. So I've got to build in a dummy load as well. Probably some neon lights or something that simple.

B

 

[Anonymous]

You know the salt water going to kill the aluminum, right?