,.. I wouldn't worry too much about the number game UNLESS something really adverse is happening in your tank,...as stated earlier,.. I think every tank settles in differently,..if your tank is up and running for six months to a year and these are the numbers that you are consistently getting AND everything in your tank seems to be A-OK .., fish,corals etc then,..the heck with it,.."set it and forget it" ...besides a few massive water changes, , lots of micro algae ,or a load of " nitrate remover" in a reactor you're doing about everything you can.,..
The overfeeding issue is a biggie too ,...the critters do not need as much food as YOU think they do so feed every other or third day and give them only what they'll eat as stated above.,...if you do all these things and you're still at 15 ppm
or so than so be it,...do your weekly pwc
and keep up good house keeping practices and you'll be fine.
My old 75 gal
tank ran beautifully at 10-15 ppm
nitrates no matter what I did to try and get them down to zero..., after a while I knew I was doing everything I could on my end to keep things clean so after a while I finally just accepted it .
My new 135 as of this morning has as close to zero nitrates as possible at this point in time but we'll see what happens over time... Good luck Scott .