aaronnorth
www.ukaps.org
As it happens I use a vivarium heating mat (I can see no difference in principle between it and substrate heating cable btw) to heat my small 45l tank it works a treat and is hidden from sight. So obviously substrate heating isn't a waste of money, especially as I got it for free ... as to whether it has any use other than heating ... now that is the question.
In principle it would drive water through the substrate - unless you disagree with the laws of physics - thus making the carbon substrate work as a buffer and a sink so it would be a great idea if it wasn't for the fact that having a carbon based substrate is in itself pointless and a complete waste of money. I take it we all agree??
I wouldn't have wanted to grow up on Lewsey Farm either so you have my sympathies ... The last time I was in Rhosesmor it didn't exactly strike me as being the life and soul of the party.
Me thinks you should have a word with Tom Barr who has been doing studies on it...
aka plantbrain on here.
here he is having a rant at someone else on ASW lol: http/www.aquascapingworld.com/forum/11920-post29.html