major things to remember about water features

1. Water level, got to keep water over top of the intake filter at all times. I personally don't like having the pump inside the viv. If you want to go pro then drill your tank for an overflow and return and house the pump outside the viv in a seperate water holding tank that the main viv drains to. This is the best way to do it with no plubming inside the tank. Step up from that would be canister filter. Remember if your water travels through the substrate its going to get tinted brownish from the tannins.

2. Water goes where it wants, especially slow moving water. Be sure to test the feature several times to watch where the water is running so you can fix any unwanted runoffs.

I personnally don't think they are worth the hassle, yes they are awesome if you get a nice one going, but they eventually all fail at some point somehow. Darts don't need it, they are more for the owner and to provide a visual.

They take up ground room for dart frogs. Dart frogs are much more happier with lots of ground space covered in leaf litter than they are with a water fall and pond. I personally drill drains in my tanks and let any excess water drain out into a 5 gallon bucket that i empty every few weeks. Much less hassle.