Undergravel heater

[annka5]

I've just bought a new 74gallon tank. I plant to have it lightly planted in distinct areas. I'm going to be using a coarse sand substrate, and keeping discus.
My dilemma is, is it worth adding a small undergravel heater cable, just where the plants will be, and in the deepest part of the sand, or not?
I don't want to get a thermostat due to the £££, but thought a low wattage cable in such a big tank would be unlikely to cause any overheating. Could always switch off in warmer weather anyway.
However, don't want to spend the money on a gimmick, and if I do add it, want to do it before i set the tank up.
Any comments?

 

[Lateral Line]

I've read all the theories, and I've tried running in substrate heating cables and under tank pads. I've never found them to make the slightest difference.

Coarse gravel is not really good for plants. Similaly, the higher temperatures of Discus tanks do not favour a lot of plants.

With your choices that limited, I would think the heater cable or whatever wiould be entirely superfluous.

 

[annka5]

Yep, that makes sense. It's sand rather than gravel I'll be using, but the temp will be high for plants. I'll not be planting that densely, either.
The marketing blerb was convincing - and I didn't want to regret not having one!
Thanks for the tip