We have Lauda E100 circulating water bath unit in our lab.

Here is the link I could find on line:

http://www.biosurplus.com/store/products/5003160-lauda-e100/

You may search "circulating water bath" in Google for more options.

Instead of using a pump, have you considered running your gels in a 4C cold-room?

I also agree with Joshua Geltz. You could use lower temperature room (

u can also put in cool packs(polar packs) in the tank to keep your gel cool

In our plant physiology department scientists run their blue native gels in a fridge. The power supply of course stays outside but the thin wires of the gel chamber easily fit through the door seal. On the other hand I'd recommend a Lauda system as Arti said or simply connecting the chamber to the process water access if you have one.

We use cheap aquarium pumps (under 30$) for the purpose (http://www.eheimna.com/products/detail/6/category). They circulate up to 1000 liters (270 gal)/hour. If you supply a large enough water container (>25 liters/6 gal) you would not even need to cool the water provided that the lab temperature is 25°C.

I have not used for above purpose, but I know about water circulating pump used in coolers or in a fountain (Fountain pump), which are cheap and submersible with 1 meter head and you can get in locally.

We use Hoefer Refrigerated Circulating Bath model: RCB 300. Another proposal is to run your gel keeping the chambel in ice-bath. We applied this for mini-Protean III with success.

If it helps you can but the recirculating pump from biorad for the pfge apparatus, though this is an expensive option it would provide more even cooling that placing in a fridge or cold room.

you only need the cooling module from this set CHEF-DR II Chiller System #170-3727

Thanks everyone for your answers/suggestions. I decided to go with a pump from VWR. It looks like it'll get the job done.