Welcome, I'm always really happy to see a fellow michigander here at PT. AND you have a 90 gallon tank!?!?!?!? sweet . . . .
I think one of my biggest problems is my substrate...?
Well you didn't really specifically state any problems, so I assume it's general unsatisfaction? Inability to grow some moderately hard-hard plants?
I'd suggest it's first having to do with your lights. The actinic blue lights do not contribute much (if anything) toward plant growth, so you really have an effective 130 watts of light on that 90 gallon tank. Not an over-abundance by any means.
besides the lighting, DIY co2 on a 90 gallon is almost a given to be insufficient. Pressurized, as I'm sure you have read and will read, is reallly the way to go for reliably strong growth.
Lastly, fertilization will be an issue once the first two (light/co2) requirements are met.
To sum up, in order of importance:
The substrate is mostly asthetic, as any substrate can be enriched with fertilizer. Are you unhappy with how it looks? Sometimes "regular old gravel" can have a very natural feel to it.
Welcome again, and remember: read a lot, and ask questions!