Tomatoville® Gardening Forums - View Single Post - Diatomaceous Earth as a seed starting medium

RayR · May 4, 2012

DE is not calcareous at all, at least not the UltraSorb, there may be trace amounts of calcium Carbonate in there but Diatoms make their shell out of silicon dioxide. I think the closer you get to a pure DE deposit, the closer to a neutral PH you will get. I don't think you are going to find the PH specified on bags of DE sold as absorbent products, I only verified the PH of the UltraSorb by testing it with my PH meter.
You could use a horticultural grade DE which naturally would require it to be around a neutral PH, but at least around this area you are only going to find it sold at a hydro store in a granule size about like Perlite.

May 4, 2012	#19
RayR Tomatovillian™ Join Date: Jun 2010 Location: Cheektowaga, NY Posts: 2,466	DE is not calcareous at all, at least not the UltraSorb, there may be trace amounts of calcium Carbonate in there but Diatoms make their shell out of silicon dioxide. I think the closer you get to a pure DE deposit, the closer to a neutral PH you will get. I don't think you are going to find the PH specified on bags of DE sold as absorbent products, I only verified the PH of the UltraSorb by testing it with my PH meter. You could use a horticultural grade DE which naturally would require it to be around a neutral PH, but at least around this area you are only going to find it sold at a hydro store in a granule size about like Perlite.