Ultrasorb vs perlite

[Father'sDaughter]

If you read through the DE thread here (which is now quite long), some people have tried absorbents that are not 100% DE and had problems. The key is to read the bag and make sure it's all that's in there. I can't remember if the Napa product is mentioned in that thread, but most of us are using the Autozone version. There is also a Blue Ribbon brand kitty litter that is 100% DE, but again, one needs to read the label as Blue Ribbon has several different types of kitty litter and not all are 100% DE.

And yes, I too wear a mask when handling it. Once it's in the pots and wet, the dust is not longer an issue.

[RayR]

Originally Posted by Father'sDaughter

If you read through the DE thread here (which is now quite long), some people have tried absorbents that are not 100% DE and had problems. The key is to read the bag and make sure it's all that's in there. I can't remember if the Napa product is mentioned in that thread, but most of us are using the Autozone version. There is also a Blue Ribbon brand kitty litter that is 100% DE, but again, one needs to read the label as Blue Ribbon has several different types of kitty litter and not all are 100% DE.

And yes, I too wear a mask when handling it. Once it's in the pots and wet, the dust is not longer an issue.

The NAPA branded DE was mentioned in the seed starting thread. I personally rejected the NAPA DE purely on the fact that it tested at a PH of 6.0 and wanting to compare apples to apples to a peat based seed starting medium in the PH range of 6.5-7.0, I found the Moltan DE to be perfect for that. So I never tried the NAPA branded DE for a seed starting medium, but I did use it as a minor amendment in garden soil and in containers.
Those folks like kevn357 that did try the NAPA DE as a seed starting medium experienced growth issues with seedlings. I read on GW that another person had the same problem. At first I speculated it may be the lower PH that was the issue, but then someone said that ProMix has a PH of 5.9 and it worked fine for seed starting, so how could PH be the problem with the NAPA DE? Fair enough.
I've been thinking something else is going on there. Anything that is mostly Silicon Dioxide like DE or Perlite should have a PH of about neutral. So the lower PH of the NAPA DE has to have something to do with the impurities in it that are different from what comes out of the Moltan mine. So I've got a new theory that would explain it. I noticed the NAPA DE had more colorful aggregates in it that were very noticeable when it was wet indicating that there were more oxide impurities in it than the Moltan DE. Non-metal oxides react with water to create acids, that would account for the lower PH. Possibly the types of acids created are having a negative effect on seedling growth?
Using the NAPA DE as a minor component like Perlite in a potting soil or in garden soil won't likely create any problems. I haven't had any. But as a major component or the only component in a seed starting medium the results are quite different.