char is like a sponge and attach, the pumice and lava rock will absorb the nutrients also,but the char will hold on to it,the roots seek out the nutrients of your soil and the char provide it,char also without being charged will rob your soil of the nutrients and suck it into the char,leaving the empty void ,in turn seeking the char for the nutrients,so you can go over board using it, what size pots are you using?
thing about char ,as you feed, water ,it continue to sponge it in were pumice and lava rock just runs off but both are great for air,as far as a charge of it,what is your plan for feed to the plants,organic i hope or your wasting time in my opinion,salts will build up in it with synthetics and almost impossile to flush ,plus you cant flush soil period,wont happen,what will is a pot of clayish mush and compacted to a point that it will never mend itself before you harvest.
so with that being said i use knf methods and they are my nutrients ,i feed soil not plants,let say you plan to use 5 gal bucket soil,
fox farm trio nutrients,in that bucket of soil you would use about a inch worth the char to fill the bucket of soil,doesnt sound like a lot, designed to add as you go,like when you amend your no till soil,so fox calls for a certain amount for seedlings ,veg,bloom always start at 1/4 strength right? if all you plan to charge is that 1in of char in the bucket stated,take the feed as you would for that feed and make 1gal,after you made the feed,just pour in a container the char,then the feed till you cover the char with liquid,that is charging it friend,i would also add earth worm castings,but thats it,let it sit for a week or so,the longer the better and it not robbing your soil nutes if you dig,the less time you dont charge it,the more nutes it sucks from your soil.
anyway hope you can understand what im talking about,char is great stuff and really is great source,been used for years,just keep in mind,this ,and i plan on doing a side by side one day,with char,it going to be like using a soil that has had slow realese nutrients already added to the soil,so let the plant tell you when it needs more and go slow and easy on dose of feeds you put in,till you get the sweet spot,also all that juice you have after charging the char,make tea from it,hope i helped
