substrate heating

["Gordon L. Mc Lellan III" <gordon at dimension-x_net>]

I've trying to DIY a low-voltage substrate heating system, and have read
several of the articles on the net regarding the subject.

Not being a big fan of math, and with the limited resources available,
here's what I've come up with;

I have a 50 watt 12 volt transformer that once powered a low-voltage halogen
light.

I have approximately 12 feet of 30 gauge copper/tin wire woven in a
snake-like pattern on some craft canvas.

I have a 10 gallon aquarium, filled with 2 gal of water for testing

The canvas is about 1/4" from the bottom glass suspended by some rocks

When I connect the wire to the transformer, the small amount of 30 ga wire
that is out of the water gets warm, but the coils under the waters I cannot
feel any temperature difference.

I assume that I must have too much resistance / too long of wire, and that
is why it's not getting hot, or is my voltage too low?  I first tried 5 and
9 volts, and the exposed wire didn't even get warm with them.

Should it get warm enough that you can feel it, or doesn't it work that way?

If I remember high school circuits class correctly, would running another
'snake' of wire near the first one, and wire them in parallel to the
transformer, this should cut the resistance in half, which should generate
more heat?

Thanks for any suggestions,

Gordon