API pH Down Freshwater Aquarium Water Treatment
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About API Water Conditioners


It’s Smart To Be Proactive!
The best way to keep your aquarium clean is to maintain good water quality. This will help keep your fish strong and vibrant and prevent disease. Water conditioners and test kits from API can help you keep your aquarium water safe and healthy.
How Do I Maintain a Healthy Environment?
It is important to test your aquarium water weekly to ensure it stays healthy for your fish. In addition, a bi-weekly partial water change of no more than 25% will help reduce toxic buildup, remove debris the filter missed, and replenish the oxygen available to your fish.

Feed Twice Daily and Test Water Weekly
Feed your fish twice a day, check their water temperature, and observe them to make sure they are active. You should also test water quality weekly for optimal safety. For fish to thrive, their water must closely match that of their natural environment—poor water quality can cause stress, illness and even fish loss. The 6 important parameters for healthy aquarium water are ammonia, nitrite, nitrate, pH and water hardness (GH & KH). All of these can vary over time and are invisible to the eye.
Change Water and Restore the Ecosystem
In a closed aquarium environment, there are no natural rivers or streams to carry away debris and other waste materials. That is why you should replace 25% of your aquarium water every two weeks, making sure to add water conditioner to your tap water to make it safe for your fish. You should also change your filter media and clean your gravel monthly. Adding beneficial nitrifying bacteria with API Quick Start when you do will help restore your aquarium’s fragile ecosystem and avoid disruption.

What Do API Products Do and When Do I Use Them?

API Test Kits
Use test kits weekly to monitor water quality parameters, which can vary over time and impact the health of your fish.

API Stress Zyme
Using this every week will help keep your aquarium clean and your gravel and ornaments sludge-free.

API Algaefix
Use weekly to control algae growth and keep aquarium glass, ornaments and plants clean.

API Stress Coat
Use every 2 weeks during water changes to make tap water safe, and when adding fish, or when fish are injured.
About API
The team at API has a passion for fish and understands the rewards and relaxation fishkeeping can bring. For almost 60 years, they have developed premium products with a focus on proven and effective results. API offers a range of testing kits, water conditioners and nutritionally superior fish foods. They are dedicated to making a better underwater world for the benefit of fish and those who keep them.

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Price | $4.85Chewy Price | $4.85Chewy Price | $9.29Chewy Price | $2.92Chewy Price | $2.88Chewy Price |
Autoship | $4.61Chewy Price | $4.61Chewy Price | $8.83Chewy Price | $2.77Chewy Price | $2.74Chewy Price |
Fish Type | Tropical Freshwater, Goldfish, Cichlid, Betta, Bottom Feeder | Tropical Freshwater, Betta, Goldfish, Bottom Feeder, Cichlid | Cichlid, Tropical Freshwater | Tropical Freshwater | Betta |
Aquarium Type | Freshwater | Freshwater | Freshwater | Freshwater | Freshwater |