Congratualtions on deciding to put together a vivarium! Nothing beats a small piece of the rainforest in your home.
I hope that you are not planning on keeping these two types of frogs together, as a single species setup will be far more successful.
Though red-eyes and dart frogs share the the same geographhic areas in many cases, they occupy incredibly different microclimates. Dart frogs generally inhabit the forest floor and the understory, living their lives amongst the leaf litter. umidity is ncredibly high, and temperatures are generally in the hgh 70's. Here is where the problem arises; Red-eyes live far higher up in the trees. This means that they are subject to higher temperatures and far lower humidity. How does this tie in? Well, For red-eyes to remain healthy, they MUST be allowed to dry out periodically. They cannot tolerate ultra-high humidity all the time, as after a rain storm in the rainforest, it gets incredibly warm and much dryer in the treetops when the sun pops out. This then, would cause some major problems for the dart frogs, as you should never let the humidity in the vivarium go below 80%. To house these two species together then, a 30 gallon tank would be far from appropriate to create both of these microclimates. Instead, your minimum tank size would have to be at least 6 feet high, and this would still be a juggling act.
If you would like a successful vivarium, I would stick to either dart frogs OR red-eyes. Though I have both, I think you would enjoy a bold species of dart frog far more, as they are far more active, and you will have a much better chance of breeding them.. which I beleive is an incredibly enjoyable aspect of thie hobby.
Now, should you chose dart frogs, I would stick to a single spcies here as well. Inter-species aggresson can be a big problem in mixed dart frog tanks. Also in a mixed seting, you run the risk of hybridization... which should not occur under ANY circumstances.
If you are interested in dart frogs..... I highly recommend purchasing them from Mark Pepper at Understory Enterprises. He has the largest collection in the country, and produces the best frogs. His website is below:
www.understoryenterprises.com
Though he is located in Ontario, shipping to BC is generally not a problem, even in cold weather.
Good luck, and feel free to ask as many questions as you like.
Double J