Tank is slipping into algae hell - help

[somafish]

What's your nitrates? Nitrates+phosphates =algae. Everyone is so quick to say ro/di water only,change up your lighting schedule and get more filtration. I use tap water, 12 hours with 8 bulb t5 and leds and a SWC 180 (granted I love this skimmer) no other filtration other then chaeto in a refugium, in a moderately stocked 120 gallon tank (but ran the exact same setup in a clown breeding set up which was fed 3× a day) and the only place I get any algae is frag plugs.
I have seen so many people with the same problem as you, and I can only think of 2 reasons why(other then bad husbandry,I don't know if it's the case with you) 1st broadcast feeding, especially as much as you are feeding, I only spot feed make sure all the fish are there for dinner and ad a little at a time, just cuz your food is gone in 15 seconds doesn't mean it's in the fish. 2nd sand beds I can't stress this enough. Shallow or deep it doesnt matter,they are nitrate traps and I believe the culprit behind many unexplained tank crash's
In the end i do everything your not suppose to and i have never dealt with algae and those are the only reasons I can figure why