perlit,how much should i use

using black gold and this nothing else...what % of mixture of perlite...I hear 25,30,40 and 50 % someone told me 50% with black gold..sounds a little much

Frankly, it really boils down to preference. When I used to do use soil, about 50% was what i would like to mix in. However, the more perlite you had, the higher your watering frequency you have and less of a buffer for pH and EC fluctuations. So if you are planning on using Chem nutes, and almost treat your soil grow as hydro, mix away. however if your goal in a soil grow is ease, just add 10% and mix in organic amendments. Lots of good soil recipes on here.

Generally, use about 25%, when making my soil.