Hello, Dorothee,
I can only agree with Michael.
I have not one single tank which has more technical equipment than lighting. I have tank volumes of 12 liter, 16 liter, 25 and 27 liter, 54 liter and 120 liter – and none with filters, pumps, heating …………….
As Michael says – it’s only a question of water changes (I change about 25 to 30% each week; more disciplined in the smaller tanks than in the bigger ones) and feeding.
I only feed live food – even to the fish which would also take dried food – as most of my fish only consume live food it makes no difference to me.
And I can only recommend to put some shrimp into each tank …….. the best cleaning team I’ve ever seen. Caridina simoni lives and reproduces even in the kind of water that paros prefer.