General Article: Tank Setups

Substrate Heating System

by Bob Nuckols

Okay, okay? I am finally writing a fish article I promised Gas months ago. In my defense it has been busy around here. I switched jobs and had a new baby who seems to know when I am on the computer trying to do something productive or just chatting in the fish room.

The first thing I am going to write about is a substrate heating system. This system is designed to heat the substrate to insure even heat throughout the tank. The fish folks that will find it most useful are plant devotees. The heat coming from the substrate encourages root growth. This idea is stolen from the nursery industry who keeps their plants on a heated table.

While I like "building things myself " I am not very brave about the idea of putting electric cables (i.e. Dupla) into a body of water. It was a drawback to substrate heating. While at my new job I discovered a machine they call a ground heater. It consists of a furnace, a pump, and about 500 yards of rubber hose filled with anti-freeze. They string the hose out in loops, the furnace heats the anti-freeze to 500 degrees and that in turn heats the ground so that the construction workers can lay concrete in freezing weather.

You might wonder what does this have to do with fish? Well, I took the idea of tubing, a heat source and a pump and made a tank heater.

First, I went to the local home improvement store and I bought poly pipe -the type you use for running water to ice makers, a bunch of plastic wire ties (zip ties), and egg crate light diffuser and a small waste paper basket. Then quick trip into the local fish store to buy a small power head, and a small submersible heater.

I cut the egg crate material a half inch smaller than the bottom of the tank. I next looped the poly pipe around and around the bottom of the egg crate, placing them as close together as I could without kinking the pipe and zip tied it to the egg crate.

Next came hooking up the pump to the poly pipe, that turned out to be a little bit of a challenge but a short piece of half inch cpvc pipe, a cap and airline to airstone adapter. (I found this last item in Lee brand disposable airstones). I used a maxi-jet 750 pump and the half-inch cpvc pipe fit exactly over the output.

A cap on the end with a small hole drilled to insert the airstone to airline adapter and I was in business. No clue was necessary or used so I could take it a part and clean it if it was necessary. The pump was ready to be suction cup attached to the bottom of the waste can.

I next used the suction cups to attach the heater to the side of the waste can. I used a Hagen brand heater but any that will fit in your wastebasket should work.

I made a little hanger for the wastebasket out of an old piece of acrylic and a couple of nylon nuts and bolts. Then after I put the poly pipe/egg crate grid into the bottom of the tank and covered it with substrate I hooked up the poly pipe to the pump and made sure the other end was in the wastebasket. Next I set the heater to eighty degrees. After a few hours the tank was also at eighty. So the heat produced in the tube did heat the substrate which in turn heated the water.

The only problem I found was the water in the wastebasket did evaporate quickly and needed to be checked often. I would suppose a cover of some kind would help with that problem. Also a lot of heat energy was wasted because the wastebasket was not insulated. I think I will use a small "playmate" type cooler next time.

I suppose that this egg crate/poly pipe grid could be used in a plenum type system for nitrate reduction for either saltwater or freshwater tanks. I have seen it speculated on the Internet that substrate heat might make plenum type saltwater systems work more effectively but I have not gotten that far with it. If anyone wants to experiment with that let me know how it works.

Article Copyright ©2001 by Bob Nuckols, all rights reserved.


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