I will give you some info on this. I seeded a pumilio 20 gallon high terrarium (80 liters) and added frogs the same night, 4 weeks ago. I didn't go crazy with the number of springtails I added. I can now see a few springtails in the substrate from the outside of the terrarium. This is the terrarium on FrogTV channel 1. I would expect the numbers go swell within the next month. Some times it can take 3 or 4 months to have a large population established, and remember the frogs will eat them continuously, which is partly why some people set up terrariums months before adding the frogs. The springtails I use are sold as "temperate" springtails, but I use them in all of my dart frog terrariums.