Geir, I don't know if this will help, but there is a product called Blusana
by the Leni company from Germany. It is irregularly shaped and seems to do
better than the really light round stuff. Is there any way you could get
some of that? I haven't been able to find a list of distributors yet.
Maybe you have friends or business connections in Germany? I will write
them and see if they have a distributor in Norway.
--
Reka
http://www.rolbox.it/hukari/index.html
"A fanatic is one who can't change his mind and won't change the subject."
--Winston Churchill
"Geir Harris Hedemark" schrieb im Newsbeitrag
...
"Ray @ First Rays Orchids" writes:
If the medium you used is very light or substantially spherical, it may
be
tough to get sufficiently stable. Look around for a brand that's more
irregular in shape, and it will lock-in faster.

It is. No other brands are easily available. Do you think mixing with
marble chips would be an option? They don't retain water, but they are
heavy and irregularily shaped.

I guess I could also use a lump hammer to break the spheres up a bit.

Geir