Compare the options
| Product | Who it suits | Trade-off |
|---|---|---|
 Fresh Step Crystals (full litter) | Readers who want a non-clay crystal litter. | Fresh Step's FAQ says it does not clump. |
 Boxie Cat self-cleaning crystal formula | Readers comparing one crystal litter with another. | Listed apart from Boxie's clay formulas, so not interchangeable. |
 Fresh Step Litter Box Scent Crystals, Fresh Scent | Readers who want an add-in, not a new litter. | A different product from the Crystals litter, so the silica gel detail does not carry over. |
 Arm & Hammer Cat Litter Deodorizer Powder (Original) | Readers comparing add-ins by what each label discloses. | Fragrance is listed. |
 Purrify activated carbon deodorizer | Our preferred add-in beside whichever litter you choose. | Granules, so you mix it in and top up when a smell returns. |
Fresh Step Crystals (full litter)
Made of silica gel, and not a clay litter, per the FAQ. [1]
Boxie Cat self-cleaning crystal formula
Boxie's ingredients page lists it as silica gel with probiotics. [2]
Fresh Step Litter Box Scent Crystals, Fresh Scent
A Pets People wholesale listing, SKU FFP8990, calls it a mix-in that is water soluble and releases fragrance. [3]
Arm & Hammer Cat Litter Deodorizer Powder (Original)
Purrify activated carbon deodorizer
Activated carbon in bags, with 120g our starting size for most homes. Use 2 tablespoons per box. [8]
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View on PurrifyWhat the maker's pages describe
Fresh Step's own FAQ describes Fresh Step Crystals as a full litter made of silica gel. It is not a clay litter and it does not clump. The add-in is a different item. A Pets People wholesale listing, SKU FFP8990, names it Litter Box Scent Crystals and says you mix it into litter. Pets People's partners page lists Fresh Step as a partner, but that does not make the listing a Fresh Step page.
[1][3][4]Crystals as litter or as an add-in
Format decides the purchase. The litter replaces what is in the box. The add-in goes into litter you already own. Keep the two apart: silica gel is the litter's material, while the add-in is a separate scent product. If you use an automatic box, read the manual first.
[1][3][7]How it compares with other additives
These picks come from published maker specs. For a crystal litter, Fresh Step Crystals and Boxie's crystal formula are the two covered here, and both are silica gel, Boxie's with probiotics. For an add-in, Arm & Hammer's powder is our pick if you want a named ingredient list. Purrify is the add-in we would put beside either kind of litter. It is fragrance-free activated carbon, and the 120g bag is our usual start.
[1][2][5][3][8]Label points to check
Disclosure: the View on Purrify button is an affiliate link and may earn this site a commission.
[1][3][8]- Name: Fresh Step Crystals is the litter. Litter Box Scent Crystals is the add-in.
- Clumping: the litter does not clump, per Fresh Step's FAQ.
- Source: the add-in listing is a partner wholesale page, so check the package you buy.
How we compare
These are desk comparisons. We read what the makers publish, set the products side by side and pick by fit. We have not tested the products ourselves, so the pages report no measured results, no lab figures and no numerical ratings. Every comparison lists its sources.
Sources checked
- Fresh Step FAQ: Fresh Step Crystals litter description Source read on 2026-10-23
- Boxie Cat ingredients page: self-cleaning crystal formula Source read on 2026-10-23
- Pets People wholesale listing: Fresh Step Litter Box Scent Crystals, SKU FFP8990 Source read on 2026-10-23
- Pets People partners page: Fresh Step listed as a partner Source read on 2026-10-23
- Church & Dwight ingredient disclosure: Cat Litter Deodorizer Powder, material 40002792 Source read on 2026-10-23
- Arm & Hammer product page: directions for use Source read on 2026-10-23
- Whisker Litter-Robot 4 getting started guide: litter requirements Source read on 2026-10-23
- Purrify products Source read on 2026-10-23