Poison Dart Frog Vivarium

I am starting to build my new vivarium for darts and I have some questions. I am making a small waterfall/stream that will collect in a little pool. There is a pump to keep it flowing but no filter. There will be moss and maybe one or two plants. I am worried about the water staying clean, does any one have any advice on that. Will it stay clean by itself, are there specific plants I could place into the water? I was also wondering if maybe I could put a snail in the tank? Thanks!

I never used waterfalls or had any standing water in any of my dart vivs, but I'd reccomend adding a lot of plants. The frogs love to hide and hunt in them, and the more secure places for them to hide, the safer they will feel and they'll come out in the open a lot more. Plus they really make vivs look nice if you are displaying them.

I cycle out the spring water in my red eye's viv about every 3 months.