I've just done mine, some people wait until spring. Some do there's in Autumn. I do mine now right before spring so that their putting on their new growth and looking good for this year :) hope this helps

Thanks for the advice Dandanspon - as it's finally stopped raining I'll make a start!!

Okay! Good luck with it!

Got to do the same thing but I wait until I see substantial activity from the fish and frogs. Their metabolic rate right now is still low from the water being cold(takes longer to heat up...something called delta H or change in enthalpy, if your interested in that kind of stuff, I am) ....anyway to start stirring up the pot of my ponds would cause undo stress to those living there depleteting them of stored energy needed for them to go back into normal activity. Causing them to jump the gun now at this stage could be fatal or make them very I'll.

I suggest doing it now. Our frogs (followed by toads) usually start getting active about now. It is much easier to do it before frogspawn appears. And if tadpoles have started swimming around the pond - we would leave most stuff until they had all gone.

Thanks everyone for advice - I've decided to do it now and take the risk pf disturbance, so fingers crossed.