Can i use any other fert other than what i have

[Atxpunx]

I use flourish and osmocote in my tanks and I'm wondering if it's safe to use any other granule fertilizer available at hardware stores. For instance, if the make up is the same as osmocote could it be safe to use? Where I live I don't have access to lfs, this is why I'm trying to see what I can use. Thank you for any info.