Sorry 4d3, I did reply yesterday, but for some reason it didn't go through... I think most of your queries have been covered now. as to water changes, I fill an 80 litre container with water approx. the right temp, adding seachem safe as its filling to allow it to mix, then I pump it straight into the tank from the container. I do this 3 times and that's my 25% change (the container never totally empties as I cant drain it below the level of the pump)Because im running a sump the water thoroughly mixes in the main tank before it gets chance to get to the bio media