25W Aquarium Fish Tank Submersible Heater

Bought this to replace a set temperature heater (rated at only 15 watts) that kept overheating my tank.

The thermostat in this heater is spot on according to the tank thermometer. I use it in a foot by eight inch square (ie VERY small) tank housing a siamese fighting fish and lots of plants. Had the heater for a couple of months now and I think it's pretty good for the money. The light comes on when the heater is active and then goes out when the water is back at the required temperature, the same as most heaters (except the fixed temperature ones), and it's not too bright to ruin the effect of a moonlight lamp if you turn the heater light to face the outside of the tank. I've had no problems with the holder (mounted diagonally down one of the tank ends), and the suckers have stayed put since I positioned it. There isn't much difference between heaters of this size, and given that the temperature seems to remain very stable in the tank, I think that this one wins hands down because it's so cheap. Would recommend it to anybody with a small aquarium.

Ummm all heaters come on and off periodically hence the light turning off...it will eventually turn back on.
All in all excellent for the price :-) Don't let a n00b ruin your opinion of this nifty lil heater ;-)

It takes a while to start doing anything to the water temperature, to the point where I wasn't sure if it was working or not. Since the indicator light doesn't seem to work (as in, does not light up at all), I had to unplug and feel near it to see if it was giving off heat - couldn't. Tried touching it - slightly warm, more like tepid. This was after being put in for about an hour. I'll give it the benefit of the doubt for now, as it's still new; perhaps it'll heat up quicker after more use. Also the wire with the plug is impractically short - my plug socket is about 2-3ft away from where the tank is, directly below and behind the tank, and yet I've now had to put books, magazines and a small box underneath to push the extension lead closer (because I don't want the extension just suspended in the air). I've given it 3 stars for now, because apart from the indicator light not working, it heating slowly (although I'm not sure if this is standard, this is my first heated tank), and the cable being too short, it seems like it'll do the job, and for £8 I guess this'll do.