Thanks for the comments... I haven't moved my mantis into the aquarium yet because after moving 2.5g salt water from my display and adding 2.5g fresh salt, my cat stuck it's paw into the aquarium. I'm thinking I'm going to need to drain and redo the water because who knows what a cat has on it's paws (kitty litter?), or maybe just run carbon this week. The mantis didn't like the krill I tried to feed him even though he hit it a few times. It might have been stuck to the chopsticks a little hard for him to grab. Need to work on my enticing skills. He has eaten some mysis that made it into the sump when I was feeding the display.
Another thing I have noticed is that there is a good amount of surface scum. I have a toms aquatics surface skimmer on order that I will either rig up to work with the Whisper filter that came with the setup, or use for water changes. If I'm not satisfied then drilling the tank should be easy since it is acrylic, or buying a second 5g and placing them side by side and making the display overflow into the second tank then pump it back.
Side note, these aquariums are nice especially if you place four of them in a circle and use weld-on to stick them together. Then you just cut slits into the sides to make one overflow into the other until you get to the last one that pumps back to the first. You can either make one display with a sump aquarium, refuge aquarium, and return aquarium, or something between that with either two displays or three displays with the sump/refuge/return being part of the remaining aquariums. Each tank will have their own LED lighting.
David