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An Undergravel Heater

Nadeem Faiz (faiz at me.udel.edu)

Materials needed:

  1. Any waterproof support structure
  2. Power supply of sufficient wattage
  3. Wire wrap wire (No 28 or No 30, can be purchased from Radio Shack)
  4. miscellaneous hardware (nuts, bolts, etc., as needed)
  5. 3/32" shrink wrap tubing

The wire wrap wire is passed through the shrink wrap tubing first, to protect the wire. The tubing is shrunk using a hair dryer. Note that the size of support, and quantity of materials are dependent on the size of the aquarium (see The Krib's Plant Tech section).

[Diagram]

To determine the length of wire, follow calculations listed below:

Assume number of gallons = G, or Liters L = 3.78 * G
Then Watts needed W = L * 0.1
Assume Voltage used = V, then Resistance required = R [ohms] = V2 / W
Resistivity of Copper (rho) = 1.673 x 10-8 [ohm meter]
Then Length of Wire of diameter A = L [meters] = R * A / rho
For No 28 Wire, L [meters] = (V2 / W) * (0.0804 * 10-6) / (1.673 * 10-8)
For No 30 Wire, L [meters] = (V2 / W) * (0.0503 * 10-6) / (1.673 * 10-8)
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This page was last updated 29 October 1998