Until a more senior member wades in, I guess I'll try to help.
Do not throw out any of your potting media, it all can be used, and can turn out high quality trees.
You can grow trees in just about anything if you understand how to water, how often and how the media affects watering frequency, and how your local water quality affects the media you are using. The choice of media and your water quality will also determine the best options for fertilizer. So it is a complex subject. I've been serious about bonsai for 2 decades or more and still don't have any easy answers. The vagaries lead to ''Soil Wars'', relax, remember there is more than one way to raise a tree. Its okay to not listen to the loudest expert in the room. (it includes it is okay to ignore me).
Before anything else, uniform particle size is important for root health. All potting mixes are improved by being uniform in size. Largest and smallest particles should be within a quarter inch of each other in size, (within 0.5 cm give or take) it is not exact, but a wide range in particle size will compact over time, loose air voids, and not hold much water, and when wet will become poor in oxygen. A fine mix, that has been carefully sifted to a uniform particle size can have just as much in air voids as a coarse mix. Key is uniform particle size. All commercial mixes are improved by removing fines by sifting before use.
Personal bias, I usually will not use any single component mix. Single component mixes have been at the core of a number of disasters in my 30+ years of bonsai experience. The one exception has been pumice. Pumice alone has been okay. Kanuma alone has been okay. That is it. Akadama alone also has been a problem.
Pumice - When you read the mixes that successful growers use - meaning you have seen photos of their trees, and they look good, and you see evidence they have done this more than 5 years. Pumice will be the most frequently occurring component of the many, many different mixes different people use. Pumice is excellent.
Perlite - wonderful stuff. I use a lot of it. Mostly for my orchids. BUT, I also use it in place of pumice in bonsai mixes. Perlite in its properties closely resembles a light weight pumice. Use perlite instead of pumice - but remember, because it is lighter than pumice, you must match the other components weight wise. In a bonsai pot a layer of moss on top of the perlite based mix will help hold it in place. Perlite based mixes are too light to hold a tree stable in a shallow bonsai pot. Its okay in deeper pots used for azalea. A layer of moss over the perlite will hold it in place.
Bark - wonderful stuff - it is ''organic'' with good CEC, and it provides food for mycorrhiza - the symbiotic fungi that most trees rely on in nature. Because bark slowly decays, it slowly turns into dust like mud, its properties will age in the pot. This is a good thing. Decomposing bark will keep a potting mix mildly acidic. This is useful in raising azalea, maples, hornbeams, beech and other trees requiring a mildly acidic potting mix. Bark based potting mixes, where bark is a third or more of the mix, should be repotted once every 3 to 5 years. Don't let these mixes go much more than 5 years without repotting. The usual recommendation is to start with composted bark, which is just bark that has already been wet and allowed to decompose for 3 to 6 months before being bagged and sold. Composted bark will last a year or so less in a mix before breaking down. I use fresh bark and let the ''composting'' happen in the bonsai pot. No harm no foul. Never had a problem with fresh bark.
50:50 Perlite and Bark - this is an excellent mix for azaleas. It is also a good general nursery phase mix for growing out trees. It is light weight enough that large nursery pots won't require 2 men and a boy to lift. You won't slip a disc throwing around pots with this mix.
Granite or Quartzite. The two minerals are interchangeable in bonsai use. Quartzite is metamorphic granite - chemically it is still mainly silica. Granite mined out of Georgia tends to be bright white with black flecks. Quartzite out of New Ulm, Minnesota is called ''Cherry Stone'' and is a wonderful, reddish purple gray, with brown and some black. The color is slightly purple at a distance. Makes a wonderful top dressing because of its nice natural and neutral color. Both are crushed and sold as poultry grit. I like the ''layer'' grade, and ''turkey'' grade for bonsai. ''Grower'' grade is a finer grind, ''Layer'' is more coarse and ''Turkey'' is 1/4 to 1/2 inch size.
Granite was the ''go to'' for bonsai from the early days through until more modern techniques were brought to the USA by students studying in Japan. The big plus for crushed granite - it is available in any size particle you want, it is totally inert. A tree potted in a well sifted granite media can remain in the same pot for 5 decades without repotting if that is what one wants to do. It does not break down in human timescales.
Downside to granite - it does not hold water inside the particle - It can require more frequent watering in summer, less in winter, and there is little margin for error. Once it is dry - it is bone dry. Granite is heavy. You can not toss around large trees in granite - you will need a strong back and or help. Young guys use granite - us oldsters use lighter products. Because granite is not porous, it has no CEC to speak of. It does not hold fertilizer, it does not buffer the environment around it. For example, bark buffers the water film around it to slightly acidic conditions via tannins and other soluble wood products slowly leaching into the water film around the bark. Granite has zero in this respect. Mycorrhiza can not penetrate granite, nor root hairs, it is just there.
You can make a bark & granite mix, 75% granite and 25% bark is the old timer's standby mix for pines & spruce. 50:50 bark & granite used to be the go to mix for deciduous. These mixes worked, if you watched your watering, but were heavy. And because the granite portion holds no water, were prone to suddenly get too dry on a hot day. Little margin for error with watering.
The 3 together - bark, perlite & granite - is too large a weight difference in the particles as
@sorce mentioned. They will settle out.
Napa Oil Dry - only part 8822 - this part number is % Diatomaceous Earth. Other part numbers are clay products and will turn to mush on you. Diatomaceous Earth - DE - is fossilized skeletons of diatoms. Basically pure silica dioxide - but in an open lattice that held a small single cell organism inside. It is fantastically porous, holds huge amounts of water and air, providing both moisture for roots and oxygen for metabolism. Great stuff, at least in theory. I have and do use it, so I'll go back to great stuff. Napa 8822 is ground rather fine. It is a much finer particle than most other common bonsai media, and if you remember the uniform particle size rule, and the no single component rule, it is hard to find a commercially available product in the right particle size range to use DE 8822. This is one reason most that use it tend to use it as a single component mix. It holds a huge amount of water, and fertilizer. It takes a little practice to get watering right. Good news it holds air well enough that over watering is not an unusual danger, it can be over watered, but it fairly resistant to overwatering.
There are coarser grades of DE out there. Maidenwell mines in Australia used to ship 1/4 inch and 1/2 inch size bags of DE, but they stopped distributing in the USA, and I haven't found another source in over 15 years. I'm sure it is out there, just need to find it. DE is mined somewhere in the desert southwest, New Mexico perhaps?
Napa 8822 is a good size match for Pumice from ''Dry Stall'', available from Rural King and a few other farm supply stores. Not to be confused with ''Stall Dry'' which is some wood chip product. Dry Stall is a fine gray pumice in a particle size that is close to the same size range for Napa 8822, and I used a blend of 8822 and Dry Stall for a number of years until I bit the bullet, and bought a pallet of a coarse pumice. A group of us pitched in and we bought 3 pallets, I've got another 5 years worth under a tarp in the backyard. No, I'm not selling or sharing, it was a pain to get it, I'm going to delay the repat of the problem as long as I can.
Perlite & DE Napa 8822 is a good blend if you can match particle size. If you can find a fine bark, Perlite, Napa 8822 and Bark is a really good blend.
Horticultural grade charcoal - as an orchid grower, most orchid supply houses carry charcoal, in various size grades. I always like adding a small amount to my mixes, about 5% to 10 % of the total mix. I never see it for sale anywhere other than orchid supply houses. It has been fading from use in orchid circles. Benefit - it has a high CEC, and mycorrhiza love it. Read agriculture articles about the addition of ''biochar'' to soil for increased productivity.
Turface - another product that the most common form is a bit on the fine particle size, could be good in a blended media. I got away from Turface entirely a number of years ago, then found a coarser grade of it and have given it a ''okay in small amounts'' approval. I recommend to never use Turface as more than 25% of a total mix.
Turface is a calcined clay. Mined somewhere in Virginia. It is NOT the same as Diatomaceous Earth chemically. Turface is a clay, it is not pure silica. This means it contains amorphous forms of various calcium, magnesium aluminosilicates, and a whole bunch of other silicates, some sulfates and all kinds of mostly silicate products. If the caline process was complete, Turface resembles its cousin, crushed brick. It holds a lot of water. Particles tend to have one or more flat surfaces, when used in too high a percentage of a mix, especially bad as 100 % of a mix, it will settle and loose air voids. When blended with other products with more random shapes, this is no problem at all. Some people like it, some hate it. I am now ''officially agnostic'' on the subject, I use it as an additive at less than 25 % of my mixes. And not at all for my azalea. Others say it is okay for azalea, but that is where I thought it was causing problems when I used to use it.
There are some serious long time bonsai growers that swear that the only things one should use are the same ingredients the Japanese use, Akadama, Kanuma and Pumice. The Akadama and Kanuma products are volcanic clays, not at all like Turface. It would be a mistake to think Turface is anything similar to these products. They do work. If the price tag is not an issue, it is okay to use them. I avoid them when I can. They do work, they are pricey and not always available.
I have used mixes with granite-bark-turface-pumice & charcoal, with good effect.
So these are how you can use what you got, and if you add Napa 8822, and or Turface, and or Dry Stall, and or charcoal to your line up you can make some really nice 3 to 5 component mixes.
