Pets · Head-to-head
Seachem Flourite Black vs CaribSea Super Naturals Peace River
Which should you buy? Our verdict on both, pulled from our full The Best Aquarium Substrates: 4 Compared (and One to Skip) comparison.
Flourite Black is the rare substrate that helps plants without touching your water chemistry, and Seachem says it never needs replacing. Peace River is the cheaper, gentler choice if your tank is built around catfish, loaches and other fish that sift the bottom.
Seachem Flourite Black
Buy itA porous clay gravel that feeds plant roots without moving your pH, and that Seachem says you will never have to replace.
- Seachem states it is not chemically coated or treated and will not alter the pH of the water.
- Seachem states it is good for the life of the aquarium and need not be replaced, so there is no exhaustion clock.
- Seachem says gravel modifiers such as laterite are not necessary, so it works as the whole substrate bed.
- Dusty in practice: Seachem calls it pre-washed but still says it may need rinsing, and its own support answer covers people still getting heavy clouding after washing.
- No grain size is published, so you cannot check it against barbeled bottom dwellers.
- It does nothing to pH, KH or GH, so it will not help you if your goal is softer or harder water.
CaribSea Super Naturals Peace River
Buy itThe smooth 1.0 to 2.0 mm river sand CaribSea itself names when asked what to put under corydoras.
- CaribSea's FAQ answer on substrate for corys and other bottom dwellers names Super Naturals as very smooth-grained and Peace River as its favorite.
- Published typical grain size of 1.0 to 2.0 mm, so you can actually check it against your fish.
- CaribSea markets the sand-sized Super Naturals as all natural with no paints, dyes or coatings.
- No plant nutrition of any kind, so rooted plants will need root tabs or a nutrient layer underneath.
- CaribSea's FAQ says to rinse it before use, which is a real chore on a large tank.
- CaribSea makes no buffering claim for the Super Naturals line, so it will not correct water that is too soft or too hard for your stock.
Side by side
The 8 criteria below are the ones our full comparison judged every product on, narrowed to these two.
| Seachem Flourite Black Our pick | CaribSea Super Naturals Peace River | |
|---|---|---|
| Our verdict | Buy | Buy |
| Best for | Planted-tank keepers who want to choose a substrate once and never revisit it. | A community tank built around catfish, loaches or anything else that sifts the bottom. |
| Price tier | $$ · mid-range | $ · budget |
| Material as described by the maker | Fracted porous clay gravel | Natural river sand, no paints or dyes |
| Stated effect on pH | Will not alter pH | No buffering claim made |
| Published grain size | Not published | 1.0 to 2.0 mm typical |
| Rinse before use | Pre-washed, but maker says it may still need rinsing | Yes, CaribSea says rinse first |
| Replacement interval stated | None needed, good for life of aquarium | None stated |
| Plant nutrition | Mineral-rich clay, laterite not needed | None, use root tabs |
| Maker guidance for bottom dwellers | None stated, a separate sand version is sold | CaribSea names it their pick for corys |
| Package sizes | 3.5 kg and 7 kg | 5, 10, 20 and 40 pound bags |
Which one is right for you?
Pick the Seachem Flourite Black if
planted-tank keepers who want to choose a substrate once and never revisit it.
Know before buying: dusty in practice: Seachem calls it pre-washed but still says it may need rinsing, and its own support answer covers people still getting heavy clouding after washing.
Pick the CaribSea Super Naturals Peace River if
a community tank built around catfish, loaches or anything else that sifts the bottom.
Know before buying: no plant nutrition of any kind, so rooted plants will need root tabs or a nutrient layer underneath.
The bottom line
Our overall pick is the Seachem Flourite Black - A porous clay gravel that feeds plant roots without moving your pH, and that Seachem says you will never have to replace. Choose the CaribSea Super Naturals Peace River instead if a community tank built around catfish, loaches or anything else that sifts the bottom.
Want the full picture, including the other options we compared and the popular one we'd skip? Read the complete The Best Aquarium Substrates: 4 Compared (and One to Skip).