Is kalk profitable to sell on Amazon United States?

The niche generates $41K/yr across 12 tracked products. 0 of 2 products launched in the last 360 days are still selling. 90-day search growth is -8.6%. Flapen's verdict: Skip it (38/100).

How competitive is the kalk niche?

6 brands and 16 sellers compete. The top 5 products take 75% of clicks and top 5 brands hold 98% of demand.

What does it cost to enter the kalk niche?

Listings span $7.34–$51.54; the average listing price is $21.62 (sweet spot $15–$100). The average incumbent carries 174 reviews — the moat a new listing must climb.

kalk

Skip it

Brand-locked demand (top 5 brands take 98% of clicks) — this niche doesn't clear our bar today.

Avg price

Great$21.62

avg listing price — sweet spot $15–$100

Review moat

Great173.67

avg incumbent reviews — the moat a new listing must climb

Returns

Great1.3%

return rate — above 6% kills the launch gate

Price range

Great$7.34–$51.54

cheapest to priciest tracked listing — scored on the share inside $15–$100

Conversion

Good4.5%

search→purchase rate — share of searches ending in a sale

Quality gap

Bad4.6★

avg incumbent rating — lower means beatable quality

Growth

Bad-8.6%

90-day search growth — must beat 0% to launch

Competition

Bad75%

top-5 click share — a locked-up shelf

Market size

Bad$41K

$41K/yr · 41K searches

Brand share

Bad98%

top-5 brand share — brand-locked demand

According to Flapen's Amazon United States niche tracking, kalk is a $41K/yr Amazon United States market (41K searches/yr). The top 5 brands hold 98% of demand. Verdict: Skip it — 38/100.

Data updated Jul 17, 2026 · scored weekly · How we score niches

kalk market data

Units sold / yr: 2K–2K; avg 0–100/product
Revenue / yr: $32K–$43K; units × avg price
Launch success: —; 0 of 2 new (360d)
Conversion rate: 4.5%
Avg BSR: #750
Page quality: 0%
Prime: 100%
Sponsored: 42%
Out of stock: 10.0%
Avg brand age: 134 months
Avg seller age: 171 days

Competition & brand share

The top 5 products capture 75% of clicks — a locked-up shelf that new listings rarely crack.

Brands

6 flat

Sellers

Top-5 brand share

98%

Top 20: 100%

Top-5 click share

75%

Top 20: 100%

Open market

Seachem41%
Brightwell Aquatics33%
Continuum Aquatics12%
Bulk Reef Supply10%
Gingerbread Pet Supply2%
Perfect Corals2%
Open — no brand owns it (0%)

Demand

Weekly Amazon search volume, last 15 weeks — -8.6% search growth over the last 90 days.

Open Trend

Top kalk search terms

kalk23K/yr +12.7%0.0% conv.
kalkwasser11K/yr -22.6%8.0% conv.
kalkwasser for reef tank8K/yr -25.7%9.7% conv.

All search terms

Top kalk products on Amazon

Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.

Beatable (≤4.3★) Contested Strong incumbent (>4.7★)

All 12 tracked products in this niche — three views at once, no toggling.

Top sellers

by 90-day click share

Seachem Reef Kalkwasser 500gram

Seachem$20.204.7★463 rev

Brightwell Aquatics Kalk+2 Kalkwasser Powder for Reef Aquariums 450g

Brightwell Aquatics$27.864.6★244 rev

Continuum Aquatics Reef Basis Kalkwasser - Calcium Maintenance Powder for Marine Fish and Reef Saltwater Aquariums 225 g

Continuum Aquatics$13.384.4★29 rev

Seachem Reef Kalkwasser 1 Kilo

Seachem$28.514.6★80 rev

Bulk Reef Supply Pharma Kalkwasser Calcium Hydroxide Saltwater Coral Reef Aquarium Dosing (4 Pounds)

Bulk Reef Supply$33.784.7★33 rev

Newest

by launch date

Gingerbread Pet Supply Reef Kalkwasser Powder High-Purity Calcium & Alkalinity Additive for Marine Aquariums Maintains pH Supports Coral Growth

Gingerbread Pet Supply$8.301 rev

4mo ago

Kalkwasser High Purity Calcium Hydroxide - 2.25 lbs (1 kg / 1 020 g) Balanced Method to Maintain Calcium and Alkalinity in a Reef Tank

Perfect Corals$20.132 rev

7mo ago

Bulk Reef Supply Pharma Kalkwasser Calcium Hydroxide Saltwater Coral Reef Aquarium Dosing (4 Pounds)

Bulk Reef Supply$33.7833 rev

1y ago

Brightwell Aquatics pH+ Alkalinity Booster for Reef Aquariums 125 ml

Brightwell Aquatics$7.34198 rev

10y ago

Brightwell Aquatics Kalk+2 Kalkwasser Powder for Reef Aquariums 450g

Brightwell Aquatics$27.86244 rev

13y ago

What buyers say about kalk

What buyers praise and complain about, mined from review topics.

What buyers love

Quality-Overall33%

“Great product”

Ease Of Use33%

“Easy to use and it WORKS”

Value For Money17%

“And The price was excellent”

Advertised Vs Actual Product8%

“Met my expectations”

Water Flow8%

“Is affective For making quick ph adjustments to my well water making it safer for my fish”

Top return reasons

Leak-Proof24%

Functionality-Overall12%

Compatibility-Overall12%

Advertised Vs Actual Product12%

Product Condition12%

Water Resistance12%

Smell6%

Ingredients-Overall6%

Value For Money6%

Common questions

Is kalk profitable to sell on Amazon United States?: The niche generates $41K/yr across 12 tracked products. 0 of 2 products launched in the last 360 days are still selling. 90-day search growth is -8.6%. Flapen's verdict: Skip it (38/100).
How competitive is the kalk niche?: 6 brands and 16 sellers compete. The top 5 products take 75% of clicks and top 5 brands hold 98% of demand.
What does it cost to enter the kalk niche?: Listings span $7.34–$51.54; the average listing price is $21.62 (sweet spot $15–$100). The average incumbent carries 174 reviews — the moat a new listing must climb.