yeah would have been bacterial bloom. as far as filtration goes, i don't believe you can have too much!! i have a 90l tank with a fluval u3 internal and a APS 600l/h filter. glad the cloudiness is getting better!!
just for future reference, fishless cycling is the preferred method but if you are going to do a fish in cycle, tetras are not the best fish to add in the first instance. they can be very sensitive to fluctuations in water chemistry. for 'first fish' try to go for something hardier next time like guppys or platys. yours seem to be doing fine though so well done! keep up the good work with the water changes and let us know how things are going.
L.