question about vermiculite and diomatacous earth

[greg1186]

I work at a pool company, building in ground pools... we use gigantic bags of vermiculite for pool base.. the company that makes it is whittmore... I was wondering if it is safe to put in my garden and we also use diomatacous earth for pool filters... is this safe to use also?

[sheeshshe]

if you are using it around food, you probably would want food grade DE I would think...

[rkunsaw]

Diatomaceous Earth is very safe.

[DoubleDogFarm]

Are you thinking about using the DE after it has been used as filter media?

I wouldn't use it after chlorine and other chemicals have ran through it.

Eric

[greg1186]

no, I will not use it after its been in a filter..... any knowledge about the vermiculite anyone?

[stella1751]

Greg, I asked the same question last year, and we had a pretty good discussion about it. Unfortunately, I just went through all my old postings, and that thread appears to have been deleted

I had bought a huge bag of raw vermiculite to replace the perlite I normally use in my soil to aid in water retention. My local garden supply store was out of perlite and suggested I substitute vermiculite.

I researched it at the time, posting my results in response to other members' assertions that vermiculite shouldn't be used. My response included a great link I had found about vermiculite's use in a 1980's (or 1990's) study in Africa. Yes, vermiculite can be used successfully in agriculture.

Here's what I remember about that research:

• Pre-1990's vermiculite was linked to cancer because some of the mined vermiculite contained asbestos. There was quite a scandal involving a Libby, Montana, vermiculite mining concern. Allegedly, the owners were made aware that asbestos caused cancer, but they continued to mine their bad stuff, anyway, and miners were dropping like flies.
  
  There are two kinds of vermiculite on the market. Both have agricultural applications, but the fluffy stuff, which kind of looks like popcorn, has been superheated to achieve that fluffy state, which requires, according to HG, a waste of resources. In addition to agricultural applications, the fluffy stuff, which is what I believe you have, is used for insulation and other industrial applications.
  
  The kind I have is, I believe, raw vermiculite, just the flakes, which looks like mica and probably requires as much natural resources to mine as it does to bale a couple bales of hay.
  
  Vermiculite got its name because when superheated, it expands into a worm-like blob. Vermi=worm. In its raw state, it is a naturally occurring mineral, much like calcium.
  
  Vermiculite added to the soil aids in water retention, as mentioned. It also improves nutrient uptake in the plant. There was a third benefit to it, but I can't remember what that was.

Long story short, I am using mine. I prefer perlite, mostly because you can see the perlite chunks, and the raw vermiculite merely makes the soil glitter. Whether or not it helped my plants grow better can not be determined. I didn't conduct an experiment, but following is a picture of the squash I grew last year in soil amended with vermiculite:

[img]https://i801.photobucket.com/albums/yy292/mitbah/squash_1-1.jpg[/img]

Those are patty pan squash, which I have since read are favored by some as a container squash. I have good soil, though, so I can't give the vermiculite all the credit for these squash. I can tell you it doesn't hurt. All of my beds now have vermiculite in them, and my plants are having no soil-related problems. (Weather related, yes.)

I like vermiculite. I will continue to use what I have until it is all used up. I will then try to replace it with perlite, which I prefer. If my local vendor is still out of perlite, I'll buy another bag of vermiculite.

If you want me to search for that controlled study on vermiculite done in Africa, please let me know, and I'll do my best.

[stella1751]

I kept looking, and I finally found the link by narrowing my search terms:

[url]https://www.helpfulgardener.com/forum/viewtopic.php?t=18177&highlight=vermiculite[/url]

Here's where we discussed vermiculite last year. The link to that article should be in one of my posts.

[applestar]

DE used for pool filter is DIFFERENT from DE used for agricultural/horticultural use and is NOT SAFE. Pool Filter grade DE is processed with high heat until they shatter into sharp pointy structures, and they pose significant health risks if inhaled. Agricultural DE is raw mined screened particles and is often added to feed grains to eliminate bugs. They can cause some eye and respiratory irritation but is not as hazardous as the processed product. Ag grade DE is also sometimes fed to animals as dewormers, and there are food-grade DE used as health product for human consumption as well.