Answers in red.OK so I know that for Isos it is best not to have them in too large of a culture or they wont always find each other and reproduce.
Dwarf species do seem start better in smaller size culture containers, but I go straight for a shoebox with giant oranges.
How many do you need to start a population in a tank like my 40b then?
I like to keep them as a culture until there are at least 100, then take about 50n to try to start them in your viv. Remember to feed your frogs heavy before you release them and also to bury them in the leaf litter so your frogs don't immediately eat them all.
Also, I havent been able to find how long iso cultures can last. I know springs can last for years, is it the same with isos if I made a plastic shoebox size culture?
Yes it is. Actually though, some springtails may need their substrate periodically replaced or they could crash after a year or so.