Does fine vermiculite hold more water than coarse?

It has been a consent among the users of the PF-Tek, that the fine vermiculite can hold more water than the coarse variety.

I wanted to quantify this, and made a test:

120 ml of vermiculite were measured, weighed and then water was added to it until the vermiculite was saturated.(according to the PF-Tek for Simple Minds).

The 2 varieties used are the ones in this photo:


Test results:

Fine variety:
120 ml vermiculite, weighs 14 g, can hold 54 ml water.
Coarse variety:
120 ml vermiculite, weighs 14 g, can hold 46 ml water.

As you can see, the water holding ability varies considerably between the 2 varieties. If you don't take this into account when preparing substrate, it will be either too wet or too dry.

by Anno

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