What is Diatomaceous Earth? A Comprehensive Guide

Diatomaceous earth (DE) is a naturally occurring, siliceous sedimentary mineral compound from the fossilized remains of diatoms, a type of hard-shelled algae. Essentially, it’s the skeletal remains of these microscopic aquatic creatures, ground into a fine powder with a multitude of uses.

The Amazing World of Diatoms

Diatoms are single-celled algae that thrive in oceans, lakes, and rivers worldwide. These microscopic powerhouses are responsible for producing a significant portion of the Earth’s oxygen and form the base of many aquatic food chains. Their unique characteristic lies in their cell walls, known as frustules, which are composed of silica (silicon dioxide). When diatoms die, their frustules accumulate on the bottom of bodies of water, forming deposits that, over millennia, transform into diatomaceous earth deposits.

These deposits are then mined, processed, and categorized into different grades based on their intended use. The type of diatom species present, the degree of fossilization, and the purity of the deposit all influence the properties and quality of the resulting DE.

Types of Diatomaceous Earth

There are two primary types of diatomaceous earth commercially available:

Food Grade Diatomaceous Earth

Food grade DE is generally considered safe for human consumption and animal feed additives. It is derived from freshwater sources and undergoes a more stringent purification process to remove impurities. It’s often used as an anti-caking agent, an insecticide, and a dietary supplement (though the efficacy as a supplement is debated). The key here is purity and quality control. Always ensure the label clearly states “food grade” before consumption.

Filter Grade/Industrial Grade Diatomaceous Earth

Filter grade or industrial grade DE is often sourced from saltwater deposits and is treated with heat, a process called calcination, which alters its crystalline structure. This calcination increases its silica content and makes it more effective as a filtration agent. However, this process converts a portion of the amorphous silica into crystalline silica, which can be harmful if inhaled. Therefore, industrial grade DE is not safe for human consumption or for direct contact with animals. It’s predominantly used in swimming pool filters, industrial filtration processes, and as an absorbent.

Understanding the Properties of Diatomaceous Earth

The unique properties of DE stem from the intricate structure of the diatom frustules. These microscopic shells are highly porous, with numerous tiny holes that give DE its impressive absorbent capacity and large surface area. These qualities make it an ideal material for:

• Absorption: DE can absorb significant amounts of liquid, making it useful for cleaning up spills and as a desiccant.
• Filtration: Its porous structure allows it to trap particles, making it an excellent filtration medium for various liquids.
• Abrasiveness: The sharp edges of the diatom frustules make it a mild abrasive, useful for polishing and cleaning.
• Insecticidal Properties: DE’s abrasive and absorbent properties damage the exoskeletons of insects, leading to dehydration and death.

Applications of Diatomaceous Earth

DE’s versatility has led to its widespread use across various industries and applications. Some of the most common uses include:

• Agriculture: As an insecticide for controlling pests in gardens and on farms.
• Animal Health: As a feed additive for livestock to control internal parasites and improve digestion (food grade only).
• Filtration: In swimming pool filters, beer production, and water treatment.
• Industrial Applications: As a filler in paints, plastics, and rubber products.
• Personal Care Products: As a mild abrasive in toothpaste and skin care products (food grade only).

FAQs About Diatomaceous Earth

Here are some frequently asked questions to further clarify the use and properties of diatomaceous earth:

FAQ 1: Is Diatomaceous Earth Safe?

Safety depends entirely on the grade and intended use. Food grade DE is generally considered safe for human and animal consumption when used as directed. Industrial grade DE, especially in its calcined form, should never be ingested and should be handled with care to avoid inhalation of dust. Always wear a mask when handling industrial grade DE.

FAQ 2: How Does Diatomaceous Earth Kill Insects?

DE works as a physical insecticide, not a chemical one. Its microscopic, abrasive particles damage the waxy outer layer of insects’ exoskeletons. This damage causes the insects to dehydrate and eventually die. It’s effective against crawling insects like ants, fleas, bed bugs, and cockroaches.

FAQ 3: How Do I Apply Diatomaceous Earth for Pest Control?

For effective pest control, lightly dust the areas where insects are present or suspected, such as cracks, crevices, along baseboards, and around plants. Avoid applying DE in heavy layers, as insects need to come into contact with it. For outdoor use, reapply after rain.

FAQ 4: Can Diatomaceous Earth Be Used in the Garden?

Yes, food grade DE is a safe and effective way to control pests in gardens. It can be used to control aphids, slugs, snails, and other garden pests. Be sure to avoid applying it to flowering plants when bees are active.

FAQ 5: What are the Benefits of Adding Diatomaceous Earth to Animal Feed?

Some people believe that adding food grade DE to animal feed can help control internal parasites, improve digestion, and boost overall health. However, scientific evidence supporting these claims is limited and often contradictory. Consult with a veterinarian before adding DE to your animal’s diet.

FAQ 6: What is the Difference Between Amorphous and Crystalline Silica?

Amorphous silica is the naturally occurring form of silica found in food grade DE. It is considered relatively safe. Crystalline silica is a more structured form of silica that can be harmful if inhaled. Calcination converts some of the amorphous silica in industrial grade DE into crystalline silica.

FAQ 7: How Do I Choose the Right Diatomaceous Earth for My Needs?

Carefully consider the intended use. If you plan to ingest it or use it around animals, only use food grade DE. For filtration or industrial purposes, industrial grade DE is more appropriate. Always read the label carefully and follow the manufacturer’s instructions.

FAQ 8: Can Diatomaceous Earth Irritate Skin or Eyes?

Yes, DE can be mildly irritating to the skin, eyes, and respiratory tract, especially the industrial grade. Avoid direct contact and inhalation. Wear gloves, eye protection, and a dust mask when handling DE.

FAQ 9: Does Diatomaceous Earth Expire?

Diatomaceous earth itself does not expire in the traditional sense. However, it should be stored in a dry, airtight container to prevent it from absorbing moisture. Moisture can reduce its effectiveness as an absorbent and insecticide.

FAQ 10: Is Diatomaceous Earth Harmful to Beneficial Insects?

Yes, DE can harm beneficial insects as well as pests. Use it judiciously and avoid applying it to areas where beneficial insects are likely to be present, such as flowering plants when bees are active.

FAQ 11: Where Can I Buy Diatomaceous Earth?

Food grade DE can be found at health food stores, garden centers, and online retailers. Industrial grade DE is typically available at pool supply stores, hardware stores, and industrial suppliers.

FAQ 12: How Long Does It Take for Diatomaceous Earth to Kill Insects?

The time it takes for DE to kill insects depends on the insect species, the amount of DE applied, and environmental conditions. Generally, it takes a few hours to a few days for insects to dehydrate and die after coming into contact with DE.