New to Hobby, Inherited tank with new house, boy do I need help.

[Murminator]

How much live rock do you have? It is ok to have HOB filters for flow but remove the sponges (nitrate factories) they are good to have to hide carbon bags in. The 1st way to get rid of high nitrates is to find out where it is coming from. I would say you bio-load sounds ok feeding, sounds ok, so maybe it's big clogged sponges or the substrate.I see you listed crushed coral as substrate which crushed coral i seen some that is like sand and i seen some that is like big chucks...think it called reef bones. If it is the bigger stuff it can really trap junk in it if it is I would S L O W L Y change it out couple scoop fulls a week. But the 1st thing to find out is where it is coming from water changes help but doesn't totally get rid of it. If you have a stinky basement full of garbage opening the window couple times a month will help it but doesn't get rid of it getting the garbage will get rid of it.

Also check see if some had maybe put a plenum or an undergravel filter I seen some oldschool freshwater guys do that that would put nitrates up