Home > Semi-Hydroponic Culture > Inert Media Comparison > Early Experiments > Buoyancy
One of the initial issues related to media is the stability in the pot. If the medium is too buoyant, it may have a tendency to float when the plant is watered. Additionally, if the particles are too uniform in shape, they do not "lock" themselves into place, and are too easily moved during handling of the potted plant. With either one of those cases, the plant will find it difficult to gain a foothold, and may not flourish.
Evaluation of the buoyancy was done by filling 300ml clear plastic
containers with media, and then adding sufficient water to fill the
container to its rim.
As you can see from the photo above, the Taiwanese material floated considerably more than the others, about 1.25" above the bottom of the container. By comparison, the Aliflor floated 0.75", with a few pebbles sinking to the bottom, while the PrimeAgraTM only rose approximately 0.5" above the bottom, again with a few sinking. Later testing of the
Stalite shale product showed essentially no
flotation.
This simple test suggests that the Taiwanese material will not be suitable due to its tendency to float out of a pot upon watering. Floatation is not merely a matter of buoyancy, but is also related to the interlocking of the particles of the medium, and again, the extremely spherical nature of the Taiwanese material renders it a poor choice. Both the Aliflor and PrimeAgraTM brands have irregular shapes, and "locked" reasonably well in the pot. The same is true of the expanded shale
Stalite, which - being a crushed natural product, rather than a formed material - has more of an angular shape, as shown
on the previous page.
Home > Semi-Hydroponic Culture > Inert Media Comparison > Early Experiments > Buoyancy