Yea I'd then only get 1 or 2 lower watt one's.
Well see now that's why I told ya what causes it, you're at your tank not me...so you know best what's going on
Honestly I'd not do a blackout on this tank at all for a while. You say "1 months living there" so this tank really only been running for ~4 weeks? Yes your bacteria is outta wack because its not fully established yet! So keep up weekly or 2x week w/c at around 40% until such point your NO3 comes back farrr less or 0 permanent.
The bacteria you HAD established by washing it under tap water you killed it. IFFF your filter is really clogged and you have to clean it, so that when you do a w/c and then clean the pads in the tank water ONLY. And if you have 2 pads or 1 pad 1 wheel - Only clean 1 at a time and next week the other; but really only then when its near clogged not every week and ONLY in tank water so you won't kill the bacteria each time.
Is your tank having live plants? Then no carbon at all...If you don't have live plants; carbon really only works so long and generally used if a tank is medicated for some reason; i'd only then exchange pads when they fall apart and not exchange carbon 1x month or so that's silly IMO.
But that right here explains your issue: Careful how you clean the filter, do weekly or 2x w/c and only feed 1x day or every 2nd day and this algae will soon start subsiding as your bacteria builds up.