10 Best Aquarium Water Treatments 2025: According to Reviews | Chewy

The 10 Best Aquarium Water Treatments

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How we created this aquarium water treatment list

We leveraged input from our veterinarians and artificial intelligence to identify key considerations to help you find the best aquarium water treatment.
We scanned thousands of customer reviews and ratings and scored each product based on its performance against each of the key considerations. We then considered how popular a product is with Chewy customers and combined that with its key consideration scores to create the list of the best aquarium water treatments.

Key aquarium water treatment considerations

Compatibility

Ease of Use

Effectiveness

Long-Term Results

1
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle
API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle

API pH Down Freshwater Aquarium Water Treatment, 16-oz bottle

Rated 4.6 out of 5 stars
58
$15.99Chewy Price
($1.00/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.7/5
Excellent

Ease of Use

4.7/5
Excellent

Effectiveness

4.7/5
Excellent

Long-Term Results

4.7/5
Excellent

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Tropical Freshwater, Goldfish, Cichlid, Betta...
2
Tetra Correct pH 7.0 Freshwater Conditioner, 8 count
Tetra Correct pH 7.0 Freshwater Conditioner, 8 count
Tetra Correct pH 7.0 Freshwater Conditioner, 8 count
Tetra Correct pH 7.0 Freshwater Conditioner, 8 count
Tetra Correct pH 7.0 Freshwater Conditioner, 8 count

Tetra Correct pH 7.0 Freshwater Conditioner, 8 count

Rated 4.5 out of 5 stars
62
$2.92Chewy Price
($0.37/ea)
Promo, New Customers Only: Spend $49+, Get $20 eGift Card

Our ratings

Compatibility

4.5/5
Great

Ease of Use

4.7/5
Excellent

Effectiveness

4.3/5
Great

Long-Term Results

4.6/5
Excellent

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Tropical Freshwater
3
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle
API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle

API pH Up Freshwater Aquarium Water Treatment, 4-oz bottle

Rated 4.5 out of 5 stars
53
$7.08Chewy Price
($1.77/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.2/5
Great

Ease of Use

4.1/5
Great

Effectiveness

4.1/5
Great

Long-Term Results

4.2/5
Great

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Tropical Freshwater, Betta, Goldfish, Bottom Feeder...
4
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle
API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle

API Proper pH 7.0 Aquarium Water Treatment, 8.8-oz bottle

Rated 4.1 out of 5 stars
62
$11.19Chewy Price
($1.28/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.2/5
Great

Ease of Use

4.4/5
Great

Effectiveness

4.5/5
Great

Long-Term Results

4.6/5
Excellent

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Tropical Freshwater
5
Fluval Sea Alkalinity Water Treatment, 8-oz bottle
Fluval Sea Alkalinity Water Treatment, 8-oz bottle

Fluval Sea Alkalinity Water Treatment, 8-oz bottle

Rated 4.3 out of 5 stars
4
$7.99Chewy Price
($1.00/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.6/5
Excellent

Ease of Use

4.6/5
Excellent

Effectiveness

4.6/5
Excellent

Long-Term Results

4.6/5
Excellent

Is this aquarium water treatment right for my pet?

Aquarium Type

Saltwater

Fish Type

Marine Fish
6
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle
API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle

API Proper pH 8.2 Aquarium Water Treatment, 7.1-oz bottle

Rated 4.3 out of 5 stars
12
$12.39Chewy Price
($1.75/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.4/5
Great

Ease of Use

4.4/5
Great

Effectiveness

4.5/5
Great

Long-Term Results

4.5/5
Great

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater, Saltwater

Fish Type

Cichlid, Marine Fish, Marine Invertebrate, Tropical Freshwater
7
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle
API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle

API Pond pH Up Pond Water pH Raising Solution, 16-oz bottle

Rated 4.8 out of 5 stars
6
$16.80Chewy Price
($1.05/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.6/5
Excellent

Ease of Use

4.4/5
Great

Effectiveness

4.4/5
Great

Long-Term Results

4.6/5
Excellent

Is this aquarium water treatment right for my pet?

Aquarium Type

Pond

Fish Type

Koi & Pond Fish
8
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle
API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle

API Pond pH Down Pond Water pH Reducing Solution, 16-oz bottle

Rated 4.8 out of 5 stars
12
$21.01Chewy Price
($1.32/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.5/5
Great

Ease of Use

4.6/5
Excellent

Effectiveness

4.5/5
Great

Long-Term Results

4.5/5
Great

Is this aquarium water treatment right for my pet?

Aquarium Type

Pond

Fish Type

Koi & Pond Fish
9
API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle
API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle
API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle
API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle
API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle

API Proper pH 7.5 Aquarium Water Treatment, 9.2-oz bottle

Rated 4.3 out of 5 stars
12
$15.76Chewy Price
($1.72/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

3.9/5
Good

Ease of Use

3.9/5
Good

Effectiveness

4.1/5
Great

Long-Term Results

4.5/5
Great

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Goldfish, Tropical Freshwater
10
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle
API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle

API Proper pH 6.5 Aquarium Water Treatment, 8.5-oz bottle

Rated 5 out of 5 stars
5
$12.53Chewy Price
($1.48/oz)
Promo, Spend $100, Get $30 eGift Card with code HAVEFUN

Our ratings

Compatibility

4.5/5
Great

Ease of Use

4.5/5
Great

Effectiveness

4.6/5
Excellent

Long-Term Results

4.5/5
Great

Is this aquarium water treatment right for my pet?

Aquarium Type

Freshwater

Fish Type

Cichlid, Tropical Freshwater