It's hard to see which is the feed and which is drain, from the looks I'd say the feed is on the right, your drain has an elbow with an extension almost the height of the bucket, thus it won't start draining 'till it reaches that height, I'd suggest lower the height of the drain pipe or raise the buckets higher, is that shut off for the drain? if it's for the feed close it down 'till you reach proper fill without overflow.