I dont really clean mine. I brush it off using the brush from a dustpan & b set. I then lean into it (whilst jumping off the ground) and brush all the seeds into the back corner. I then get onto my knees in the front on the ground and pull the dust/seeds through by had and sweep away. I do this about once a week.
when you installed it you should have left a few cm's gap at the bottom, so you can sweep the bits out. i also just swill it with the hosepipe every so often
Sadly, I'm not 5ft10 with legs up to the ceiling so I struggle to clean out right down to the bottom of my horse's haybar on a daily basis. I bought a garden flower-bed gravel rake thing, looks like the wire rake from the scoop-plus-rake (not the thing with the curvy, bent metal "teeth") that Robinsobs sell. It's about 2ft long and means I can easily reach right down into the narrow bottom of the haybar cone to pull out any leftover hay before topping it up again. I do think they should include a tool like this with the damn thing, it costs enough! Other than that, I love mine and there's hardly any waste as long as you fluff out all your hay before it goes in. If you don't empty it daily, haylage in the bottom can get surprisingly hot!
I keep a black rubber feed skip in the bottom of mine. It soon settles into a triangular shape. I have the handles to the left and right and I find them easy to reach. I just empty the feed skip daily and it makes keeping the haybar clean very easy.
good idea putting the container at the bottom. We have them they are bril. We had a funny thing happen, somehow the back of the area in the hay bar has become soiled with ??? anyway the grey horse that is using it at the moment keeps getting covered in black something or other right from her ears to her nose, she does look funny but it's bloomin annoying and difficult to get off. Been scrubbing the wall but going to have to take the hay bar off i think and do it properly, because i can't reach to the bottom!
Could be from when a horse in that stable had a mollassed lick, but don't really know.
i left some space on teh bottom and i have one of those little witches broom type sweeping brushes on a longer handle. Just put that it and sweep it through the gap.