Unfortunately one of the little bunnies died. Apparently I gave them all too much grass to eat yesterday.
The new solar controller arrived in the post yesterday, so it was fitted today. It’s basically a digital temperature gauge which can measure two temperatures at once. When the difference in temperature between the two probes reaches a set value, a relay switches on. So I no longer need to switch the solar panel pump on manually.
Mind you, I haven’t needed to do this for a week anyway!