NO3 and PO4 too low... need suggestions

Heya guys and gals. Started using a scrubber on my newest build. Been up and running for about 6 months. I have only done 2 water changes and that during the cycle. I do, however, seem to have a problem. My nitrate and phosphate are running at 0 or close to 0. This is not optimal for many corals. Does anyone have a solution or tips . I have increased feeding to the point I am scared the fish will explode. I do not use a sock as I like my pods staying in the tank.
System:
90 gal DT 40 Gallon sump/fuge total water around 110 gallons after rock sand etc.
Avast CS2 skimmer 24 hour operation
10x12 waterfall scrubber light cycle 18 hours
Chaeto ball
had a Santa Monica HOG 3 but turned it off because the waterfall out-competed it and it did nothing but make bubbles
phosban reactor 24 hours
occasional carbon
2 part dosing

Welcome.

Yes you do have some good scrubbing now... your waterfall is 4x the size of the HOG3. But you really don't need measurable nutrients; they aren't measurable on real reefs, and thus you don't need to try to have them if you don't want to, with the possible exception of zoo's, mushrooms and leathers. You want food particles, not nutrients.

Your tank is still new though, most of the phosphate you putting into the water is going into your rocks. Somewhere at about 12 months, the rocks will be full and you are going to have nuisance algae (unless of course, you scrub a lot). So instead of feeding even more, just remove the skimmer; all those food particles and pods will now feed the corals.