Diatomaceous Earth (DE) is a naturally occurring, fine, powdery substance composed of the fossilized remains of microscopic aquatic organisms called diatoms. These ancient fossils are primarily made of silica, a substance valued for its porous structure, which lends itself to a variety of practical uses. Finding the right type of DE depends entirely on your intended use, as different grades are processed differently and sold through various specialized channels.
Understanding the Difference Between Food Grade and Filter Grade
The source of Diatomaceous Earth is determined by its processing, which results in two distinct grades with different safety profiles and applications. Food Grade Diatomaceous Earth is the variety generally purchased for household use, pest control, or as an animal feed additive. This grade is minimally processed and is composed mostly of amorphous silica, which is non-crystalline. To be classified as food grade, the product must contain less than one percent crystalline silica and meet strict purity standards for heavy metals like arsenic and lead.
Filter Grade, often called Pool Grade or Industrial Grade, is physically different because it has been heat-treated through a process called calcination. This high-temperature treatment hardens the diatom exoskeletons, improving their efficiency as a filter medium, but it also converts the silicon dioxide into crystalline silica. Filter Grade DE can contain high concentrations of crystalline silica, making it hazardous if inhaled and unsuitable for use around food, animals, or in the garden. The intended application must dictate the grade purchased, as the wrong grade can pose serious health risks.
Common Retailers for Home and Garden Use
For the consumer seeking Diatomaceous Earth for home, garden, or pet-related applications, the purchase must exclusively be Food Grade DE. The most common retail sources for this product include agricultural supply stores and feed stores, such as Tractor Supply Co., which often stock it in bags ranging from 4 to 20 pounds. These locations cater to livestock owners and gardeners, making them reliable places to find the correct, OMRI-listed product.
Major home improvement and hardware stores, like Lowe’s, as well as big-box retailers such as Target and Walmart, also carry Food Grade DE, typically packaged as an organic insect killer. The product is often sold in smaller, more manageable containers with shaker tops, ideal for household pest control or dusting plants. Checking the label for the explicit “Food Grade” or “Crawling Insect Control” designation is paramount, regardless of where you buy it. Online marketplaces are another convenient source, offering a wide range of sizes and often providing the best access to specialized brands.
Sourcing Specialized and Bulk Quantities
Acquiring Diatomaceous Earth in specialized or high-volume quantities shifts the sourcing away from general retailers to more specific industrial and agricultural suppliers. Filter Grade DE, used for water clarification, is primarily found at pool supply stores where it is sold as a precoat medium for DE filters. These suppliers sell the calcined product, which is solely intended for filtration and should never be used for pest control or consumption.
For consumers or businesses requiring Food Grade DE in large volumes, such as 50-pound bags for farming operations or commercial feed mixing, the best sources are agricultural co-ops and specialized online distributors. These distributors often have relationships with manufacturers and can offer bulk pricing that makes large-scale use more economical. Industrial-grade DE for uses like spill cleanup or specialized filtration is typically sourced from chemical distributors or direct from mining companies, often requiring a business account due to the specialized handling and high volume.