Bklyn, time is flying by actually!

You could always substitute the heavier ingredients for lighter ones.

I don't even use repti-bark..Have you thought of trying an Agway store and looking for a very good quality bark mulch. They have it every year. It costs 8 dollars for a 3 cubit bag that will last you a long time. My go to is the 5.1.1 too because there is no way around creating the 1.1.1 gritty mix without weight.

There are no agway stores anywhere around NYC.........I had a nursery that sold pine but frankly it wears out faster than Fir. hell the repti bark wears out quick. If there was a grit component that was somehow expanded but neutral chemically and therefore lighter in weight.......I'm actually hoping to hear from some that have made the leap and fooled around on their own finding lightweight substitutions.

Ken, that is very interesting. I also would love a lightweight gritty. I snooped online a bit and found this:

https://www.cospheric.com/Hollow_Glass_Microspheres_many_densities_and_sizes.html

Unfortunately for me, they seem to only speak metric and I am flummoxed (need more coffee). Still ... what an intriguing idea, hollow glass spheres. The mind, it boggles.

GrowStone, calcined shale (Sunleaves Rocks) or LECA might interest you. You are definitely entering hydroponics territory and the possibilities are endless.

Interesting ideas.

I still have a few 5 gallon buckets of hydroponic rounds. The downside of clay would be that a bucket doesn't weigh much, probably equivalent to a bucket of moistened pine bark. So, pots would be subject to flipping due to lack of weight (which happens to me with my normal 5-1-1, so I have to weigh down my pots or tie my plants down). If you don't have wind issues, they'd be great. Or perhaps, if you use some denser product with the rounds to find the sweet spot.

I'm going to try a blend of reptibark, 1/4" bonsai block (4 lbs per 2 quarts) and monto clay for a gritty test mix. I can have wind issues at times when summering outdoors (I just dragged everything back in with this cold snap).

I’ve been using bonsai mix with good results. It’s cheaper to buy the ingredients separate and mix to your ideal ratio. Akadama (Japanese granulated clay soil), pumice, and lava rock.

Would shards from broken clay pots work as a component of gritty? I add clay chunks to the mix for cattleya orchids and the orchids seem to like it. I take the broken pots and use a hammer to break into smaller pieces.

I still have the 1/4" bonsai block (4 lbs per 2 quarts) and monto clay for a gritty test mix. Haven't gotten around to it yet. Using broken clay pots would give you a lot of sharp edges I would think

I believe bonsai block is the same as haydite which is expanded shale. From their site it does look the same thing. Quite a few members in our Bonsai club prefer haydite in the their bonsai mix. A standard mix for outdoor plants used in our club is 50-50 haydite and bark both sifted to 1/8 - 1/4 inch sizes. It is indeed lighter than grit. Haydite also used for landscaping (ground cover), and concrete mixes.

Has anyone tried using those expanded clay balls, like the ones for hydroponics?

Edie: Clay shards will also work as long as it is sifted to right size. They are quite variable in water holding capacity so you will have to experiment with proportions. Crushed clay brick will work also.

All the expanded clay balls I have seen are pretty large in size. If they are available in smaller sizes between 1/8-1/4 they can be made to work I think.

Tropic, what mix is your club using for indoor plants

does anyone have a completely inorganic gritty mix that can be reused multiple times in conjunction with yearly root pruning? I would like to keep my trees in the same pot and not search for ingredients every year

For tropicals there are a few variations. haydite, akadama, bark in equal proportions, or pumice akadama and bark. The same mix some even prefer for their outdoor deciduous plants. Some use gritty mix. I do mostly gritty mix but lately I have been experimenting with more pumice in the mixture. Mainly because last year I landed on a few bags of pumice and lava rock pretty cheap.

I haven’t used it myself as a mix on its own but Lechuza (a self-watering container manufacturer from Germany) makes a mix called PON that is pumice, lava, and zeolite. Supposedly it can be reused. There is no bark - the zeolite does the ion exchange / holds onto and releases the fertilizers.

Lechuza PON seems to be made up for lava rock, pumice and zeolite. Seems to be sold out everywhere.

I did find this bonsai mix, the listed properties seems favorable. https://www.bonsaijack.com/shop/premixed-bonsai-soil/universal-bonsai-soil/2-quarts-inorganic-bonsai-soil-mix/

There are many variations in mixes and each one requires getting used to with respect to watering and fertilization. The above mix looks good too. To reuse it needs be rinsed well to get rid of excess salts. I usually keep it outside in pots for the rain to take care of rinsing and use it the next season. Before re-using I let it frst dry in Sun and sift it again. If the mix contains bark the smaller decomposed bark will be sifted out and any other minor breakdown of particles will be taken care of too. After that I eyeball and add some more sifted bark to make up for the loss.

I used Espoma Soil Perfector to replace the granite in one pot this year. It is the rocks used to make cinder blocks (expanded shale, I recon). I also have a pot with "Boons Mix" (for deciduous) bonsai soil (1/16 to 1/4 inch... 1 part lava, 1 part pumice, 2 parts akadama). Both are doing quite well.

Epsoma Soil Perfector is haydite. It was originally invented as a replacement for gravel in concrete mixes for lightweight but structurally strong concrete mix. Used in bridge construction where load is of primary concern. Recently I saw it being used as substrate for rooftop gardens. Good stuff.