Hello Jordy,
plants you can use at pH around 4-5 are:
Mayaca fluviatilis
Anubias barteri
Javafern
Javamoss
Ceratopteris
Salvinia
down to 4,5 Lymnea
with these plants you can create a very nice aquarium. I would not use a motor filter. Because it is too strong and soaks the larvae in. It is better to use a small airpump with bubble filter.
Greetings
Patrick