Floating gardens with much less substrate

I experiment for some time with low tec hydroponics. The floating device varies from plastic bottles to compressed Styrofoam.
To provide the substrate with constant moisture I found microfiber (secondhand or new) most useful.
The substrate is always aerated because it is all above water-level.

I have substrate depth between a few millimeters to 20 centimeters. Almost everything I try there grows and germinates there without much maintenance.
For a starter I use living substrate from Forrest and bogs, usually with moss and Ericales or other mycorrhizal plants.
Even some orchids germinate there like grass.

This setting keeps quite cool even in this hot summer. I was able for example to grow Meconopsis x Sheldonii from seed on one of these island at 38 Centigrade temperature without any issue.

Orchidseedling ax4.jpg