Growstone looks like a good product, though a little expensive. I'd do what the bonsai guy says. Add pumice as well. If the particles get too large, the roots won't be happy. Gritty is a fine mix, but there's a lot of other quality mixes out there. Google around for bonsai soils and you'll see a wild range of opinions.

>>Google around for bonsai soils and you'll see a wild range of opinions.<<
"Geee.... I'd never have thought of that," she said, rolling her eyes. Since she already wrote, >>I've been reading and trying to locate the Gritty Mix components so I can get ahead of the game for the season.<<

However, I do appreciate the response. Yes, it does look like a good product. My question remains, >> What would happen if I made my mixes with the larger particles?<<

Perhaps I should qualify: Is there any reason not to use particles somewhat bigger?
I'm in the process of compiling lists of ingredient equivalents. i.e interchangeable products, since some but not all are available in different areas. Kinda makes me crazy/insecure about doing further damage-to-murder of my Japanese maple collection. My babies.

I was referring more to the varied opinions on the web about different soils :) Before, I didn't realize there were so many passionate bonsai growers with their own tried and true mixes. Some hate turface, others (like Al here) swear by it.

My point was, rather than going down a rabbit hole of trying to figure out how to develop mixes on your own, just get something that a pro has already tried and used before, preferably someone in your area.

Also, there are reasons not to use larger particles. Mainly because they don't hold enough moisture or work right for the mixes.

Welcome to a new world!

>>Mainly because they don't hold enough moisture or work right for the mixes<<
Which depends upon the size of the particles. If they're all the same, which is the point of all these measurements, strainers, screens, etc., could it matter. With a product such as Growstone, whose whole point is to retain water, I go back to my original questions!

That's why I'm writing here, where I've come for over 10 years. Has anyone experience with this, or is there a good reason not to use screened particles that are bigger.

So far, no reason I can locate through months of reading and rereading. I'm just paranoid about the murders I've already done through ignorance. 12 years of murders. I take full responsibility.

Have you consider breaking the larger pieces in half until they meet the size requirement? I find growstone can be broken with a bit of effort.

That's actually what I was wondering. If I break it, does it lose porosity on the broken side? Would it matter?

There is a piece I broke in half with the exposed sides showing. That's a Canadian dime in the background, about the same size as a US dime. Looks equally porous to me though its a bit rougher than the outer sides.

Well, that's a good experiment. :) Did you just smash it with a hammer?

I just twisted it really hard. Needle nose pliers would probably work. I'd be afraid to stomp on it for fear of losing too much of it in dust. Might be worth a shot though.

"Twisted it" Hmm...

I have some of the small Growstone. I'll see what happens and let you know.

You could probably place a screw driver where you want to break it and just give it a firm tap.

My mission tomorrow...

The point of growstone doesn't seem to be 'to hold water." I looked on their site and the water retention info they showed had growstone being very similar to perlite. Nowhere near what turface and axis, which were developed to hold water, show. The point of growstones looks to be, "find a replacement to perlite from recycled materials."

uh-huh. I read that, too. Then other sources talk about water retention. In my mind, when I ran out of pearlite, I'd use the growstone I have.

You could also use it as a lightweight and somewhat more moisture retentive alternative to grit in the gritty mix recipe.

It's a thought. Going to try to break a few and see how it goes. Just got 7 Japanese maples in the mail I need to pot, so I want to do it well!