This is a "no waste feeder"...a super easy diy project. If you Google that phrase you find tons of tutorials on making them. I, too, use this type with a smaller version for my little chicks a d rhey use the big one by 7-8 weeksIf I keep the feeder 24/7 in the coop they will poop into the feed and there will be lot of wastage and cleaning problems.
Is you feeder on the ground, on blocks or hung? If not on the ground, how high up is it? That kind of feeder does tend to lead to a lot of feed waste...elevating it to the height of the birds' backs (and adjusting as they grow to keep it there) can help a lotWhat's that type called? It seems like a good solution if it is available in smaller sizes.