I spouted the seed mix you were getting from that catalog. That was in the big black cement mixing trays with the hardware cloth frame on top. I did that all outside. That worked well but they were heavy for me to handle & the chickens made such a mess eating off the tops of them.
Now I am using perforated trays with 1 pound of grain (i am using Barley now $13.50 for a 50 pound bag) in each (about 10" by 12"). I soak the grain over night then divide it up into the trays about a pound per tray & water them twice a day. I have them set up on my unused breakfast nook tile counter on a 2 shelf plastic rack. It hold 3 trays per shelf so counting the counter I have 9 trays. The bottom 3 trays are doubled with the bottom tray solid to hold the runoff water. I put sections of cut PVC pipe in the solid trays on the bottom to keep the top tray elevated from the water. It takes just minutes to soak each tray twice a day. I was using a big watering can & watering the top trays & letting it drain through to each tray beneath (like You Tube does it) but I think I like the soak method better. It is a little more trouble but I get a lot better results. This method is actually fodder feeders & not just sprouted grain but if I dumped the trays at 3 or 4 days it would be sprouted grain. In a week I have 9 trays of thick green grass about 5 inches tall. They eat it all, grass, grain spouts, roots everything.
I am eager to try the oats, $18.95 for a 75 pound bag. My daughter is on her way to pick it up at the feed store now. I have been using cheap aluminum trays from the $1 store 2 for a dollar but bought the expensive ones,$1 a piece, ( LOL ) plastic trays the other day & will switch to them this go round. Not a big investment at all. I have been reusing the cheap aluminum trays for weeks now. Maybe I will sprout oats in the aluminum ones when I switch my fodder feeders to the plastic. I have lots of holes to drill today in the 9 plastic trays........LOL.
Now I off to study more on Beehives while I wait for my daughter to get back..........LOL