As I'm new to this forum, I don't know if anyone has ever brought up this idea of saving money. If you do a calculation, or better still, realize why your electricity bill is high, know this... Your 100w element in your tank can take quite a few rands out your pocket, un-necessarily! A 100w x 50% "on" during a cold day (winter) = 1200w per day, multiply that by 30 = 36 Kw per month. Now multiply that by 0.47c = R16.92 per month. Doesn't sound too bad, but for the guy who has a bigger setup, he feels it really bad! Now a simple way to cut this cost, by at least half, it to clad your tank with a 25mm thick sheet of polystyrene. These can be cut to precisely fit the tank walls, and they can be stuck on with "press-stick" or whatever, during the night (before you turn in) and even keep them on during the day in your absence. The back wall can have a permanent covering, and possibley the sides as well, then only remove the front, when you are around. Trust me, you will save money!