Lightener reccomendations

What lightener would you recommend that I can pick up at Sally Beauty? I'm of course aware that it would be best to go get my hair professionally done but that's just not an option at the moment. I plan on using a 20 volume developer so I don't totally fry my hair. I also have olaplex 0,3,4, and 5 I've been using and will continue using after lightening my hair. My hair is a level 3 right now and my eventual goal is to get to a level 6. My hair color is not my natural color. I had black box dye in it and then used a color remover to get it to the brown color it is now.