Hi Sabrina ;
Your tank looks very clean ,is it my imagination or a few of those plants are artificial ,i am a bit baffled by your nitrate level ,40 ppm is a bit high for the number of fish you have which makes me think if you may not be able to vacuum the waist/ detritus the way you want ,not very urgent but worth thinking about before it start the health of your fish . apart from that your tank and fish looks lovely.