My 55g tank has medium gravel (slightly smaller than pea sized) on the top layer and laterite below. I found out that laterite doesn't contain a lot of macros, which explains why my swords arent doing well. My question is, is it safe to add ferts like osmocote plus gel caps or osmocote potshots...

I can't get hold of Osmocote Plus Gel Caps right now so I thought I would give the potshots a try since my swords r showing signs of N deficiency. It seems that laterite and Seachem root tabs aren't enough. As far as I can tell Potshots pretty much the same as Osmocote plus in terms of NPK...