Lighting After Blackout For Algae

Hi, not sure if this is right section to post question so please feel free to move.

I have a rio 125 stocked with guppies, rummy noses & tetras which has had a recurring problem with pea soup water despite water tests being fine, have finally cleared it with blackout for 5 days but was wondering what is best way to start up lighting so not to frighten fish & to try & prevent recurrence. Tank is situated in a dark hallway & lights are normally on 10 hours per day by timer, so any advice would be greatly appreciated,  Sam

Thanks Sue, do u think it would be best to slowly increase time lights are on say maybe starting at about 2-3 hours & slowly increasing each day,  or just put them on for normal period from day one, thanks Sam

Thanks Sue, no live plants in tank, have had tank in same place for about 3 years with no problems with algae even with lights being on 10 hours, problem only started about 6 months ago, but will try shorter lighting period