Too top it all off, the pond heater also sprung a leak, where the water was reaching the heating element seal and kept tripping the house mains, so had to remove that from the plumbing, so I've decided to order 6x400watt heaters totaling 2400watts, I have used the visitherm brand for at least 10years and had it in my recent grow out tank, so at least I can add or remove if I needed more without the hassle off replumbing and the price of these pond heaters are so expensive starting at £300 up to £2000 so buying multiple heaters at £25.00 made more sense