If you have algae in you DT, then keep it on for 24-48 hour to begin with (be aware of a temperature spike if you don't have a chiller) after that just run a "reverse cycle" when DT lights on, fuge off, when DT off, fuge on.
That's what I do. (I'm not an expert)
if you have caulerpa, you are supposed to leave the fuge light on 24/7.....to prevent the caulerpa from going sexual and release gametes and foul you water. i would suggest you use chaeto and keep reverse lighting as mentioned above instead.
btw nice duc in your avatar...which one is that?....haven't kept up with bikes in 16 yrs.
yes.... just take all the caulerpa out... get their roots also. you may have to keep an eye on it cause many times they pop back up weeks later.
DaddyReefer13 is giving away free chaeto...check it out...he's a great guy. it's the same chaeto from someone here who is selling it for a nice change.