Re: Substrate Heating Coils

> From: "shaji (s.) bhaskar" <bhaskar at bnr_ca>
> Date: Mon, 17 Apr 1995 20:18:00 -0400 
> Subject: Substrate heating coils 
> I finally broke down and decided to try DIY substrate heating.


> The only tools I'll need should be a drill , soldering iron,
> screwdrivers, and cutting pliers, all things I already have.  
> I expect the total cost of the installed heater to be under $50.
> Any suggestions/comments?
> - -Shaji

I have some info that might be useful for people wanting professional
cables for not too much expense...

A couple of weeks ago I was in our local fish shop and mentioned
to the owner about using substrate heating cables for plant
tanks, and from the back of one of his shelves he pulled out a
25W heating cable made by an outfit called Renacor (or something
like that - I can look it up when I get home).  He said he'd had
it sitting there for ages.  They also make a 50W version which
has 7m of the heating cable part (the 25W has 4m of heating

The packaging had pictures of turtles etc on it so I guess it's
mainly aimed at people wanting to keep their turtles' feet warm.
On the back of the package there is a small icon with a picture
of a fish which suggests that it's OK for aquarium use.  I looked
closely at the construction and it seems quite high quality.

The main difference between these cables and the Dupla/Dennerle
systems is these use mains voltage rather than low voltage (which
in turn means lower current than Dupla/Dennerle).  I'm not sure
what this means safety-wise (I think that lower currents are
less likely to kill), but I plan to use a GFI for safety anyway.

I went home and did some calculations on what length I need for
my tank (5'x2'x2', ~500l) and came up with around 11.5m.  The
owner managed to track down a 50W cable so now I have one of each
for a total of 75W, 11m.  Ideal.  Now I have to find some more
laterite before I tear the tank down to install them.  The site
where my wife found laterite before has since been bulldozed :-(.

Total price for both cables was under NZ$90 (~US$60), and no transformer
is required.

 Len Trigg ===================================================
 Comp Sci Grad   DoD#1334   trigg at cs_waikato.ac.nz             
 Waikato Uni     GPX250     http://www.cs.waikato.ac.nz/~trigg          
 GCS  d---(+) p c++ !l u+ e++ m* s n@ h--- f* !g w t++ r y+(*)