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Re: Heating Coils



DT writes:

>    I was wondering...and if anyone has tried this and found disaster at the
>  end , please don`t hesitate to E me .
>   I`m thinking through some methods of heating my substrate with found items
>  around the homestead . One way is to use a waterbed heater ( about 16" X
>  40" )...under the 55 G I have held in place by a board of the correct size
>  and styrofoam for insulation . It has a separate thermastat with controls
>  and is waterproof .  The other way would be to use a device from a hospital
>  I have for heating water that is pumped through tubes to a heavy plastic
>  sheet that`s almost the perfect size to go under the 55 G ....it has
>  controls to run water from room temp to 105 deg. and slowly pumps the water
>  through a little at a time . This is made for continious use and would be
>  mounted the same way as the WB heater .
>        Am I out in left feild on this ?

Well, it will heat the substrate that way, but it heats the entire substrate 
evenly.  Using coils, the water rises out of the substrate directly around 
the coil, because that is where the heat is concentrated.  As that water 
rises, it is replaced by water from the cooler parts of the substrate around 
it.  This creates what is known as "convection" currents.  These currents are 
what is believed to (and indded if they exist, actually do) bring the 
nutrient-rich water from the water column down into the substrate.

If you heat the substrate evenly, then the warm water is held down by the 
cooler water, and heat is conducted through the water without the convection 
current advantages.  Well, okay, a small amount of the warm water may make it 
out, but it will be very, very little.  You don't get the effect you are 
looking for, unless what you are looking for is to get the heater tube out of 
the tank.  For that, an underside heater is great.

Bob Dixon
Cichlid Trader List Administrator
http://cichlidtrader.listbot.com