Do It Yourself Chiller


  • Dorm-sized refrigerator (1 to 1-1/2 cubic feet)
  • 50 to 100 feet of 3/8 inch hard plastic tubing (depending, vinyl isn’t as good a choice here)
  • PVC fittings (90 degree elbows or straight connects, threaded or slip)
  • Aquarium safe Silicone sealant.
  • 1/2 inch thin-wall PVC pipe (about 1 foot for the “thru-the-box” connections).
  • Hand drill and 1/2 inch drill bit (or 5/16 inch if you prefer).
  • Screwdrivers to fit the various hardware of the particular fridge you own.
  • Eco 350 or similar pump/powerhead to push the water through the chiller.
  • Materials Cost Considerations


  • The fridge should set you back $89 to $199 depending on the size you choose.
  • The Eco 350 goes for about $28 to $50 and is available at your local hydro store.
  • The fittings, tubing and pipe shouldn’t run more than $10 to $15 bucks, depending on how much and what style you choose.
  • Hopefully you already have a drill and the bit(s).
  • My chiller ran a total of $175 once completed (without the 6 pack), still significantly cheaper than a commercial unit. While not as efficient as commercial chillers, this is a viable alternative and will draw your water temp down surprisingly well. Use a pre-set or variable heater to “balance” the temp within the sump and it’ll become “hands-free”!

Do you just need a temporary Emergency Chiller to help keep your hydro system temps down for a few days? Substitute an ice chest (even one of those inexpensive styrofoam ones will do) for the Dorm-sized refrigerator and fill it with ice. Drop the tubing coil in it and you are ready to start chilling!


“A” = Water in from sump.
“B” = Chilled water returned to sump
“C” = Freezer compartment with temp probe attached to the inside wall of the cooling box.
“D” = 3/8 inch coiled plastic tubing.
“E” = The refrigerator housing and inner plastic box.                                  

If possible, remove the metal box that isolates the ice cube tray/freezer section, but leave the temp probe alone. This will give a better overall temperature control within the cooling box. The more coils, the better the “pull-down” effect and the more efficient the unit operates. Depending on the brand/model that you are using, you may encounter insulation between the housing and the inner box when drilling your input/output holes. There is no need to seal the door. I had originally thought of this, but decided against it as I figured I might need the access if something went wrong down the road. Besides, it’s a great place to keep your additives that require refrigeration after opening (and a 6 pack!).

  1. Drill your access holes in the top or sides, it really doesn’t matter.
  2. Cut 2 pieces of the PVC pipe about 4 inches each.
  3. Insert through the holes drilled and seal VERY WELL with the silicone.
  4. You may want to reinforce these pipes with a little Devcon 5 minute epoxy prior to sealing them with the silicone. Keeps ’em from sliding back and forth and breaking the cured silicone seal should you want to move the fridge down the road.
  5. Glue or thread your fittings onto these 2 access pipes.
  6. I used nylon threaded nipples to connect the 3/8 inch tubing coils inside the cooling box.
  7. Outside, I glued slip fittings reduced to accommodate the tubing running from the Eco 350 sump pump to the chiller and back to the sump.