No offence but brushes are so noobish try just using filters and default brushes they can be very useful on LPs
I use Apophysis myself, and I'd recommend experimenting lowering the gamma settings before you render anything in the program, unless you were aiming at the grainy effect.
Before you go to render the fractal open your options field and you should see a menu that lets you tweak the gamma (the #1 killer of graininess if you lower it), the brightness and something else that doesn't seem to do jack 99% of the time. Also your choice of gradients will affect things and if you save as a transparent background (ctrl+X) you have more options when tweaking the rendered fractals in PS.
Not just gamma can fix that. Your quality and filter radius too will also help clean up the overall image. I've been using Apop for awhile now.