Keep the lights how they are, changing that wont do a thing. It seems you have got nute burn, always easier to tell if you supply pics. You shouldn't have a build up yet if you've only just started using nutes so you shouldn't need to flush. When you next need to water I would just give it good old plain water and then the time after that you should be ok to start adding nutes again.
Whenever you start adding different nutrients or are giving nutrients for the first time always start with a diluted mix. I would start at 1/4 the recommended dose and work your way up slowly, keeping a good visual over your plants for signs of nute burn. If you start to see burn again you know you have reached your plants tolerance so cut back on the nutes and keep it at that level.
Periodically it is good to flush to prevent salt build ups which will also give you burns. I would flush around every 4 weeks.