A while back, and in fact a few time I believe there has been mention of
someone who has built a device for switching off the filters for 5 (or a
configurable amount of) minutes and then turning them back on again.

The number of times I forget to switch back on my powerhead. While it is
not running a major filter I do sometimes switch off the main filter as
well.

If I remember correctly it was that man Netmax who has the plans or at
least a link to them.

Thanks

Trev