I have a 36 gallon bow front tank that has been running for almost a year. I have 7 adult guppies, maybe a dozen fries and 7 cory cats. I started researching planted tanks, since I didn't want to change substrates, I picked out the normal Java Moss, Java Fern and, Anubias. What would be a good fert for this and how much/ how often? I'm always afraid of adding things to my tank for fear of upsetting the balance.