In general, cat experts are not fond of crystal cat litter. It is made out of dried silica gel, the same desiccant packed with medications and other products -- in tiny containers or packets that are prominently marked "Do Not Eat." Some experts and owners have raised concerns about the safety of crystal litters, with Dr. Karen Becker at Healthy Pets noting that it "can be dangerous if ingested in large amounts or over a long period of time, which happens when cats clean their feet." However, there's no solid evidence that any cat has come to harm from crystal cat litters.
This type of kitty litter is popular with some cat owners for a very understandable reason: a single usage of crystal litter can last in a cat litter box for an entire month, thanks to its super-absorbency -- of course, this only applies to cat urine; you still have to scoop out your cat's solid waste every day. Because they don't have to be changed as often as clay or biodegradable litters, crystal cat litters come in more manageable bag sizes (as small as 4 pounds), a big plus for cat owners who are unable to do heavy lifting.
However, as convenient as crystal litters can be for people, cats are likely to see things from a different perspective. The tiny, jagged crystalline particles can be very hard on a cat's sensitive paws. Even if your cat consents to using a crystal litter, it may not be very happy about it. There's also a downside from the human perspective: once a portion of crystal litter has reached its absorbency limit, you'll end up with a pool of urine in the bottom of the cat litter box.
While not many brands of crystal litters receive consistently favorable feedback, Fresh Step Crystals (Est. $19 for 8 lbs.) stands out at user review sites. Including reviews originally posted at the Fresh Step web site, we spotted more than 4,000 reviews at Walmart.com, where it rates 4.7 stars out of 5. Reviewers say that the silica gel crystals do a great job of controlling odors as well as absorbing urine. Reviews elsewhere -- and that don't include feedback from the maker's site -- are much less plentiful, but still pretty good -- for example a 4.6 star rating at Chewy.com based on 75 reviews, and a 4.3 star rating at Amazon.com based on 145 reviews.
However, Fresh Step Crystals still has the same cons as other crystal litters. Not all cats will adapt to it willingly, and it's not biodegradable. You should never try to flush crystal litters, including Fresh Step, down the toilet or recycle it for compost.
Though crystal litters such as Fresh Step are more expensive than other litters, especially clumping clay litter, value is actually fairly good. That's because you'll have to change the litter box much less frequently than with other types of cat litter. How often varies, of course: Some owners posting at Amazon.com say they change the box once each month, while others do it every two weeks. Judging from reviews, you can expect an 8-pound bag to supply three to four fresh fills.
If cost is a concern, we also found some fairly good reviews for Nature's Miracle Just for Cats Easy Care Crystal (Est. $13 for 8 lbs.). It doesn't receive as much feedback as Fresh Step, and what it does get is not quite as strong, including a 3.9 star rating at Amazon.com based on around 450 reviews. Owners like the ease of use and value. This litter is scented, and that draws mixed reviews. Some call it mild and appealing, others consider it to be overpowering. Nature's Miracle otherwise has the same properties and pros and cons as Fresh Step and other crystal litters, so it is worth considering if you want to give this type of product a try.