I used 2 specimen containers 1 large, 1 small 10 bucks
1 3/4" bulk head 2 bucks
1 utube syphon hose 9 bucks
Drilled holes in the one in the 10 gallon tank and one for the bulk head in the other.
Try searching for DIY overflow. That is where I got the idea from.
Works like a champ on my 10 gallon refuge to sump. Of course next time I'll just drill a bulkhead hole in the aquarium, but I built it in a pinch.