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Re: poor man's heating cables

Susan wrote,
>For all the DIYers:

Has anyone out there tried using the heat tape made for de-icing the
edges of house roofs in place of heating cables?  I wondered if it
might work if attached to the outside of the bottom and  used with a
rheostat.  It might help if the top of the stand had an open top, if
any maintenance was needed. 
Is this a really off the wall idea, or has anyone tried it?  
-hoping I could learn by your experience/mistakes

While there are many schemes for heating the bottom of the aquarium,
they are not going to have the same effect as heating cables in the
substrate. In theory the heating cables create microcurrents which
help move nutrients throughout the substrate.

DIY heating cables using ordinary wire are very easy to build and are
inexpensive. I put mine in a year ago and it is still working fine.
The following is the post I made at that time describing my system.

For about $25 I recently installed a simple DIY substrate heating
system in my 55g tank based on the article by Dan Resler and Uwe
Behle.  Without the cable on my substrate runs 1 to 2F lower than the
water temperature.  With the cables on 50% of the time the substrate
midway between the cables runs 1F higher than the water temperature.
At 100% it is about 2-3 F higher

I used a 5amp, 12 volt transformer that I bought from All Electronics
(http://www.allcorp.com) for $11.  If you are uncomfortable with
wiring a transformer you could use a power supply for 12V outdoor
lighting which you can buy for about $40.  Just make sure it is rated
for 50W or more.

For wire I used #30 single strand WW wire which you can buy at Radio
Shack for about $3.  One post  on DIY heating systems suggest that
this wire would be too fragile to use - that is simply not true.  This
wire is very ductile and is designed to be wrapped tightly around a
.1" square post.  There is no way you are going to kink and
accidentally break this wire.

For a support system I used 1/2" pvc pipe cut into 1/2" lengths.  Half
way up on these I cut slots about halfway through.  Using a silicon
glue I tacked these on end on the bottom of the tank in 4 rows of  8
supports.  I alternated the slots facing towards the front of the tank
and then the back of the tank.  The slots on the end posts faced the
ends of the tank.  If you get the slots facing right you can create a 
continuous weaving pattern as long as you have an even number of posts
in each row.  Starting in the back of the tank go along the row
weaving the wire around the posts.  When you reach the last post in
the front row simply go around it and retrace you path to the

The ends of this wire are soldered to a heavier lead-in wire.  I made
this connection so it would be inside the tank.  I sealed the
connection first with heat shrink tubing and then with two coats of a
silicon sealant.  The wire doesn't get real hot so you could make the
connection outside the tank.  I put connectors on the lead-in wires so
I could disconnect them from the power supply.  I used a simple timing
circuit and relay to cycle the cables off and on(10min on--  0 to
10min off).  You could use a timer with 24 off or on cycles as Resler
and Behle did.  

I ended up with a resistance of 3.8 ohms or 38 watts for the system.
My wire length  was about 32' long.  As long as you keep the total
length somewhere in that ball park you should be OK.

Jim Spencer
Sayre, PA

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