I am wondering if you are using a sponge type power filter?. Have you decided to wash out the sponge?. If you have you have killed off the seeding nitrifying bacteria and basically the filtering process has stalled.
I always used to seed any new tank with a nitrifying kit (ammonia based) waited till the nitrite levels dropped then SLOWLY started to add my first hardy community fish.
Oops sorry I really don't want to fall out with anyone but I would not recommend putting mollies into a community tank in which you wish to keep the like of tetras and other species. Unless you ph is very high 8, 8.2 mollies will almost always develope white spot (ich) and fungal problems.
They are a hardwater species and will even live quiet happily in a slightly brackish tank. With the added benefit that they will start to breed like rabbits. Good Luck
