Low nitrates

[DarkSky]

I am worried that if I start feeding an additional cube or two my nitrates could blow up? How much food did you increase by and how long did it take to see no3 increase?

I doubled my feeding - one cube of mysis and a small chunk of LRS to two cubes, one mysis, one green stuff, small chunk of LRS, 10ml of acro power daily, 8 scoups of reef roids and 5 scoups of reef chili. I also added 3 fish, a yellow Tang, a royal gramma, and a yellow coris, bring my fish total up to 8. I have a 220g tank with about 275g of total system volume.

I also decreased my photo period from 8 to 6 hours on my refugium.

I also feed pellets every time I walk by the tank. Coraline has started to take off so I'm sure I'm finally getting some nitrates. Algae is showing up somewhat. Nitrates still at 0.