how important is plant specific substrate
I'm trying to get 2 10 gallons started and its turning out to cost a lot more than I thought it would. I have about 25 lbs of natural colored quartz gravel some of it is bb sized and some is slightly smaller. I really don't feel like paying 25 dollars for another bag of gravel and then i'll still have a bunch of regular gravel lying around, can't plants get along fine with mulm? from my understanding plant substrates rely on a high cec to hold onto and slowly release available nutrients, but I know I've read somewhere that mulm itself has a high cec. I've considered using a small layer of sterilized topsoil to simulate mulm buildup but I'm kind of nervous about it, never having used dirt in an aquarium before. I'm also pretty sure that I've seen beautiful tanks done with entirely inert substrate and the plant substrate thing almost seems like a trend to me. am I wrong? how much of a difference will it make?