When I acquired my new plot I planned ahead and put the ibc tank at the back of the shed to gather the runoff from the roof. Then when siting the poly tunnel I put it just down hill from the tank. Sent off for a new tap to fit the tank that will take a hose. I got worried for a bit as I thought the new tap would replace the old one and I would have to drain a 1000 litres to fit it. The new tap came yesterday and what luck it fits onto the outlet on the old tap. All fitted with a hose on a gravity run to the poly and a battery timer clock that opens and shuts the valve. I am going away for 10 days so I dug a hollow in the ground and placed all the vulnerable seed trays and pots in it. 4 minutes water fills the hollow, then drains away, but it's there long enough to dampen the plants. I had it 4 minutes every 4 hours while testing but I reckon I can get away with it every 12/15 hours this time of year although the poly does get hot with the sun shining on the south side most of the day. I'll check tomorrow to make sure things do not get too waterlogged. I'll let you now if it worked.