Your brooder is awesome
I thought mine were big! Sheesh!! But I would think 30 would be pushing it too (for ducks anyway)...my brooders are 8 x 3 x 2 and right now I have 27 chicks in one that I know will outgrow it way too fast....and 9 are bantams!
Here's a pic of one of my brooders...
Top view...
Front view.....We used the hardware cloth to help them be able to get used to seeing big people coming and walking around them.I think I read that somewhere in Storey's about that.If I have chicks that are especially vulnerable I use a piece of cut plywood to stop any drafts at their level.So far,so good!
And here's how we handle the lighting and having to raise it every week...
Anyway, the top is separated into two doors so you can open just one side at a time.The sides of the brooders have rope handles that allow you to move it (Whew! Heavy!)but they also hold a pole that fits into two grooves to hold the door open if your hands are full.(Kinda like a car hood)
The bad part is...mine are straight wood.So for ducks we had to build a platform...we measured a kitty litter pan and built a wooden frame to fit just over the top of it.We covered it in hardware cloth and put door trim backwards from the edges to help any sifted water from the ducklings "playing" roll INTO the tub.We then put handles on each side of the platform so you can pick it up...move the cat pan and dump it...replace it and WaLa!
I like your idea about the paint...I think I will designate one of my brooders for ducklings and use that idea.The poop tends to stick to the wood
so i am glad I read this thread! Always learning something new here