All of my tanks deploy some version of UGF.
- intake under the soil
Reverse - outflow under the soil
Air - air pump driven pulls water down through the soil
They all work great for shrimps. I've bred shrimps in each tank regardless of what version. I mainly use Reverse and Air for my recent tanks. Here's the pros and cons of each version for me.
Cons - seems to deplete the soil the fastest, canister filter gets the dirtiest fastest requiring more cleaning of the canister filter
Pros - Clears the tank the fastest, no prefilter needed.
Cons - need two intake tubes, need to turn off when feeding powder baby food
Pros - pushes the poop up and less mulm in the substrate, cleaner canister, easy to vac out the poop because it's always at the top
Cons- least flow compared to the other two versions, needs a larger (noisier air pump) to power the sponge filter and UGF
Pros - slowest flow so the substrate should last the longest. Clean canister.