The conical base of the silos made it not stable if it is free standing in #SilosGrowbed, with LECA surrounding and holding it in place is okay.
However this defeat the purpose of trying to use as minimum LECA as possible.
One way of holding it in place is to tie it together with string, this way it will be self standing. However the drawback is that, if you needs to replace one silos then it may be tricky to do.
Got an idea.. !!! use clips, just like those paper clips, laundry clips to hold the silos together. Made few from TIG welding wires, and looks like it may just work. Welding wire are cheap, they are rust proof, comes in various sizes and materials.
Do a quick bending and manage to get few clips from welding wires that I have laying around the house.
Hand made so the size are variable.
There you go, clip on the silos.
Will need to adjust the bend radius, to make it more tight in holding the silos. There you go, a simple solution to secure the silos in place so that it can be individually work on.
BTW, you don't need many clips to use, just enough to make it free standing especially for those in the outer part of the cluster.