Whether or not the food is consumed is of little consequence to nitrogen and phosphate levels. Most of the nitrogen, and phosphorous that is eaten is expelled as excess any way.
Feeding is artsy.
You have to judge it by your fish and the other animals in your tank.. I like variey and have always feed my fish well. A cut back in feeding unless it's truly excessive is putting the cart before the horse ,imo.
If nutrients are an issue , I'll up the ante on export with skimming,gac, refugia,organic carbon dosing .etc. If that's not your style then you have to feed less. or suffer high nutrients and the nuisances and sometimes tragedies they bring to your tank.
My system has about 40well fed well rounded healthy fish including 6 surgeon fish , and angel, a butterfly, rabbit fish, wrasses, cardinals, firefish, 3 mandarins ,5 pair of breeding clowns and more. Most have been in my care for over 6 years. Several are from day one almost 8 or 9 years ago.
I don't claim to know what the best feeding regimen is. I think most would say I feed heavily;some who might be more judgemental might say too much or the wrong types of food.
Overall, I don't think there is enough diffence in carbon,nitrogen and phosphate content in most foods to make a significant difference. Most are close to the Redfield ratio,ie 116 organic carbon to 16 nitrogen to 1 phospahte. I strive for variety and daily consistency in feeding.
There are some exceptions ,like foods with bones,silversides etc.that have high phosphate to protein ratios,krill with low nutritional value, some seafoods for human consumption which are preserved with phospahte and a few others. There are others that have exceptional cartenoid ,hufa and other content of high nutritional value like cyclopeeze for example.
My regimen works for my tanks and keeps my fish healthy. Opinion on a general best methods will vary. Pellets may be just fine and many have success with them; it's just not what I choose to do.So, I say paint your own canvass.
But since you asked here is what I do:
AM,ie,about two hours after lights on: a mix of frozen 50% mysis, 35% brine shrimp and15% bloodwrom( mosquito larvae),sprinkled with frozen cyclopeeze. Broadcast fed to each tank. It totals about 1.3 ozs of frozen food. I do thaw and rinse the frozen food with tap water;not only to remove packing water but also to sanitize it some with the chlorine in the tap water. I also rinse the foods I eat before cooking them.. After draining it out in a brine shrimp net, I add ro water and then feed with a turkey baster.
Then every other day the tanks get strips of nori along with a pinch of Prime Reef flake and some flake spirulina at the AM feeding in addition to the frozen. They also get some chunks of krill for the larger fish to enjoy.
In the PM ,about an hour before lights out, the same amount of frozen food as the AM feeding is provided ,ie,about another 1.3 ozs . No extras in the pm.
Coral Frenzy is also broadcast fed to zoanthids on occasion and what blows around feeds other corals and other animals. I'm inconsistent with this and should be a bit more disciplined with it.
Seahorses get only the frozen mix twice per day .
It is ok to run reef tanks with parsimonious feeding and ightweight nutrient export or vice versa. I like the vice versa . BTW, there are no filter socks ,pads floss ,etc. in the systmen. The food just moves around untill some thing uses it or the skimmer exports some of it.