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First Saturday Lime Review [Does it Work?]

The Verdict
First Saturday Lime is overpriced for the main ingredient essentially being chalk, and the pest-repelling claims are not well studied. We suggest skipping this product or using a cheaper alternative.
Ease of Use
The Good
Easy to use
The Bad
Very expensive for what it contains
No real proof or studies on the effectiveness of repelling pests
Loses efficacy outdoors with moisture and rain
Bug Lord Rating

As seen on Shark Tank, First Saturday Lime claims to be an “eco-friendly” product safe for children, pets animals, and organic farming. While the business model was attractive enough for one of the sharks to take a bite – the concept of using calcium carbonate and other desiccants to repel insects has been around for some time.

Keep reading for everything you need to know about First Saturday Lime in our review – including our breakdown of how it works and if it is worth the price!

First Saturday Lime 20lb
  • As seen on Shark Tank, April 10th 2020 on ABC. Same day Priority Mail shipping on orders place before 2pm CST Mon-Sat....
  • Preferred by customers who want a non-silica based solution. Removes and prevents algae from ponds and birdbaths.

What is First Saturday Lime?

As First Saturday Lime notes on their website: “First Saturday Lime is NOT a pesticide.”

A pesticide actually kills pests or inhibits their reproductive cycle, whereas a repellent simply tries to keep them out of specific areas. First Saturday Lime claims to be able to repel insects by creating an undesirable barrier of calcium carbonate to repel crawling insects. 

The main ingredient of First Saturday Lime is a derivative of limestone – precipitated calcium carbonate. Essentially, this product is made by dropping a specific type of limestone into water. You may also know calcium carbonate as chalk.

Calcium carbonate is commonly used as an anti-acid and has many commercial applications ranging from whitewash to cleaning industrial smokestacks. The company adds in some amount of citric acid – another “home remedy” insect repellent – though the exact formula remains proprietary. 

What Insects Does First Saturday Lime Repel?

First Saturday Lime claims on their website that the product will repel:

  • Ants
  • Fleas
  • Ticks
  • Lice
  • Mites
  • Aphid
  • Small hive beetles
  • Mosquitoes in water
  • and more

However, as you will see in the section below, these claims have not been specifically verified by any published scientific studies.

How Is It Applied?

The company suggests that it’s product is reapplied once a month, hence the name “First Saturday”. Application basically involves spreading the product onto the ground to create a barrier that insects will avoid.

First Saturday Lime recommends many different types of applications on different areas of your property. Here’s a short breakdown of each type:

Pets & Yards

First Saturday Lime can also be used around your home and in your yard to repel many different insects. Essentially, you can simply pour the powder into a line around a building you want to protect or whitewash walls to discourage insects from laying eggs. While there are a handful of scientific studies that suggest this may work, few scientific studies have tested precipitated calcium carbonate specifically or the application methods the company suggests.

The company claims that the product is completely safe for your family and pets – though users should be warned that these claims are based entirely on anecdotal evidence and not on rigorous clinical studies. Calcium carbonate is recognized as “generally safe,” but high levels of ingestion can certainly disrupt the pH balance of the organism that ingests it. 

Chicken Yards

First Saturday Lime offers many uses for chickens, from controlling moss growth and algae in water pans to getting healthier, harder eggs. First Saturday Lime claims that it makes a great dust bath for your chickens, and it can even be used to whitewash the inside of the chicken coop to repel insects.


The company also claims that its product is great for routine cleaning and deodorizing in horse stables. Similar to chickens, First Saturday Lime can be used to whitewash your horse stalls and keep the water trough clean.

How Does First Saturday Lime Work?

First Saturday Lime cited “years of story evidence” to back up all of their suggested uses – though the company does not provide any specific scientific evidence for these claims. Calcium carbonate has long been a “home remedy” for getting rid of insects, though there are few scientific studies that suggest it actually works as a repellent. 

The company claims that calcium carbonate works because it is a desiccant. A desiccant, when applied directly to insects, pulls the water out of their bodies and effectively dries them out. The citric acid may add a pleasant smell and additional insect defense. Though the product may form a lethal barrier to insects, there is no scientific evidence to suggest that it repels them from a larger area.

So, it is likely that insects will avoid the areas with large amounts of the product but specific claims don’t seem to be validated by much scientific study. It also may not be very cost-effective.

Does First Saturday Lime Actually Work?

Desiccants of all types are commonly used as “traditional” insecticides. In fact, the basis of First Saturday Lime is the anecdotal evidence that ants will not cross a line of chalk (also known as calcium carbonate, the main ingredient in First Saturday Lime.)

While there is a large body of evidence that multiple desiccants work as an insecticide in applications like grain storage – there is only a small body of evidence that suggests they work as a repellent. 

Is Repelling Effective?

One article posted in a Japanese journal suggests a calcium carbonate mixture can deter a specific type of moth from laying eggs on apples when it is applied as a spray. However, this is not the application method suggested by First Saturday Lime, so the research may not translate to the First Saturday Lime product.

Interestingly, the National Lime Association does not list “insect repellent” as one of the known uses of precipitated calcium carbonate. The substance has been extensively used as a water treatment, as a soil amender, as a base for roads, and in many other applications. If calcium carbonate had been proven as an effective insect repellent, one would expect to find some evidence of this compiled by the industry that creates calcium carbonate.

What Happens if it Rains?

While citric acid and calcium carbonate may remain separate when they are in powdered form, they will most certainly react when they are introduced to water. This will create carbonic acid, which usually becomes carbon dioxide. 

In layman’s terms – when it rains First Saturday Lime is going to wash away and become less effective. Some of it will turn into a gas, while some of it will wash into your soil and increase the pH. 

Since First Saturday Lime is intended to be reapplied once a month, it may still be effective at deterring insects if the barriers are constantly reapplied. However, if it is raining multiple times a week, it is likely that most of the First Saturday Lime will be washed away.

What Are Some Useful First Saturday Lime Alternatives?

First Saturday Lime is essentially Barn Lime – a product that has been used for many decades to deodorize and clean farms, horse stalls, and barns. While the First Saturday Lime formula is a “company secret,” the company clearly states that calcium carbonate is the main ingredient. Barn lime is exponentially cheaper than First Saturday Lime and it’s the same active ingredient! You can usually get a much better deal on barn lime from a local home improvement store since bags are heavy to ship.

10 Pounds Calcium Carbonate Limestone Powder Fertilizer and Soil Amendment
  • 10 pounds of Limestone Powder , Slight off-white coloring
  • Calcium carbonate limestone powder is a widely diverse product and is commonly used around farms and homesteads for a...
  • As a moisture and odor absorbent, it is used in barns and animal areas to create more favorable conditions for both...

The calcium carbonate product clearly works to some level – it has been used in various industries for 100 years. First Saturday Lime is just rebranding the same product, adding citric acid, and selling it to people outside of the farming community at a massive price increase. 

Hydrated lime – a product also derived from limestone though slightly different than calcium carbonate – has also been tested rigorously as a repellent. While it also has “anecdotal evidence” supporting its use, hydrated lime has failed against many insects, further adding to doubts that calcium carbonate is an effectively meaningful repellent.

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Written by Gabe Buckley

Gabe Buckley is a professional science writer with a Bachelor's of Science in Zoology and a Master's of Professional Natural Sciences from Colorado State University.


Leave a Reply
  1. We appreciate your time you took to make a review. I would be most interested in hearing about how it worked for you. That being said, if it worked or not. We offer a 100% satisfaction guarantee. So if it doesn’t work, there is no risk to you. You get your money back.

    This product has never existed before and we filed a patent to prove it. We took hydrated lime and made it insoluble which makes it vastly different from regular calcium carbonate which is mined from the earth and which has never been calcium hydroxide. That is not all though, our formula (which also contains citric acid) has numerous clinical studies to back up its efficacy.

    It also will not lose its efficacy when it rains. Since it is insoluble, it will not dissolve, nor release gases or change in any way when it comes in contact with moisture. Hope this helps explain how it is different from anything else on the market, namely “barn lime.”

    Our family has been in the limestone business for 3 generations and supplies all types of lime for almost every application possible. We created this product for us because we use it and it works.

    We are sorry that you are unsatisfied with your investigation into our product. Please email me your order number and I will refund you immediately.

    Thank you for trying us out! – J.M. McDaniel, creator and founder of First Saturday Lime

    • I like FSL and have seen it’s effectiveness first hand. I don’t think this article had any actual “investigating” other than an hour or so of googling.

    • I super love your product!! I personally will be buying again no matter how much shipping cost! I have tried first hand on everything your family has Suggested works for us!!

  2. I use this for my house. I had some really bad wasp nest and I got bite twice by the pool when I found a nest under my pool slide and I saw my cat get bite and found a second nest under our fence near a cat house we built her. Before I ran to the store to purchase wasp spray, I took a handful of First Saturday Lime and threw it at each nest and ran. About an hour later I came back outside and the wasp were all still on the nest but dead or dying. I was super surprised because I didn’t expect it to work but it did and I took both nest down later that day and no problems. That alone, was worth the price of the 20lb bag and I still have 19+ lbs to work with for snails and other critters.

  3. Sir i would like to know can you buy FIRST SATURDAY LIME in stores? I do not have a credit card to buy on line. I seen product on SHARK TANK and i was interested in the product from the start.

  4. I use First Saturday Lime regularly in my chicken coop and on my hens. I have zero issues with lice or mites in fact, I have no bugs in my coop at all. It works amazingly for flies inside or outside the coop. I also use to dust the backs of my horses for flies as well. It’s far better than barn lime.

  5. If the product is insoluble, why is monthly reapplication needed? Especially in a coop-where chickens bathe in it keeping it on their skin 24/7, as well as inhaling it 24/7. How is it safe for chickens to do so when people are told not to breathe it or bathe in it 24/7? Also, chickens eat it constantly pecking the ground-so if it affects ph it could lead to canker, thrush, and other issues when a chicken’s ph is off balance. Other livestock animals don’t bathe in their “hydrated lime” stall additive. Hydrated lime is the only ingredient listed on the first Saturday lime bag. I’d like to see some chicken health studies published.

  6. This is a wonderful product and I’m wondering if this reviewer even tried it before posting this? We get terrible ants near our well and if they get in the electronics they get electrocuted and cause shorts and we lose water. We also get ants in our feed bins. In addition to spreading around the perimeter of our home, I put this product around our well and in the bottom of our feed bins and we have not had an ant problem since. When we first bought it, I had an active infestation in the feed bins and it killed all of the ants. It also has minimized flies/larvae in our donkey/duck yard. I pour it under the water buckets where I would normally find maggots during fly season and have not seen any new larvae since and our fly population has dwindled dramatically. We love First Saturday Lime!

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