Does anyone have data on the actual weight of perlite versus pumice, for a given volume?
Only WAGs, no actual calculated data. IME, pumice would be slightly heavier but almost infinitely superior in use.
No, I just use them almost interchangeably, Perlite w/ Houseplants & Tropicals, Pumice w/ Succulents.
Why would you need that info? Could I pls ask what you're planning?
Perlite = ~ 5-8 lb/cubic foot (fully expanded)
Pumice = 40 lb/cubic foot
I can believe gardengal's numbers. I think pumice is a whole lot heavier.
Pretty darn easy to verify :-)
I never used perlite when I had pumice to use. Now that I don't have access to easy pumice, even though there's a mountain of it in the province (don't get me started), I still don't use perlite. It's not a good thing if you have access to better things, but if it's the only thing, it'll do.
@KarenS I am talking to a soil manufacturer who uses perlite in their mix, and I am trying to convince them to use pumice instead. The perlite floats to the top and makes a mess. They objected that pumice is too heavy.
@gardengal48 (PNW Z8/9) You came through for me on this question. Thanks!
Unfortunately, your answer confirms the fact that pumice is much much heavier. I am dealing with a soil manufacturer who wants to save weight. Since weight and transport cost is most of the cost of the product for a soil product, that's a non-trivial issue.
Thanks for explaining. I've never had the Perlite floating issue, but I only grow Indoors & I mix my components REALLY well.
Sure I can see why it would matter to them, absolutely.
Shoveling cheap pumice was a special joy, now that ya'll mention it.
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