It's turned this really deep green color, seems healthy. I run the pump for about 5-10 minutes a day to oxygenate the water to avoid anaerobic conditions. The P and K have been added, along with Fe chelate. I have removed almost all of the duckweed and I'm growing it in another small container because I find it fascinating and a strong grower (but required N unfortunately).

Not sure how to get it to grow faster though, any suggestions?