yeah bio pellets are a simpler form of carbon dosing, but some have found that when runing it all the time that you may find issues with it stripping everything out, where as some softer corals like a bit of nitrate and phosphate.
LA Fishguys, Bio Pellets, Episode 107 pt1 - YouTube
good episode on biopellets from a very knowledgable jeff at reef dynamics.
as for having hair algae issues, you're probably not seeing any because the redsea max and API kits are not the most accurate as they don't read low levels there are some kits that will though, you may also not get any levels because the algaes are already consuming all of it.
best thing i could say right now is turn out the lights and lower your feeding to once every 2-3 days and keep the lights one for a few hours a daymaybe like 4 hours to limit the growth of hair algae and promote its dies off so you can actually remove or test the levels in the take in order to maintain dosing levels