Hi Arno,
I know that.:) I’m going to use my three existing tanks (that are now fully planted) most likely as community tanks. In any case, not for Paro’s. I need to buy some more (small) tanks. In those, I plan to use some floating plants that are found in blackwater habitats.
Thank you for the recommendation of the sponge filter. I will see if I can find it here, or something very similar.