I water my plants from the top of the container & I noticed that after a couple weeks the soil/hydroponic growing medium starts compressing. Is that bad & if so how do I fix it?

Yes, it is. Soil/hydroponic growing medium needs to be light & fluffy in order for oxygen to get to the roots. The best way to stop the soil/hydroponic growing medium from compacting is to add perlite before planting. There are many different formula’s that people use from 50% soil/hydroponic growing medium with 50% perlite, to 100% straight perlite. Perlite holds oxygen because it is porous. It is very hard to over water when using straight perlite.