--- product_id: 17923261 title: "API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle" brand: "api" price: "€ 11.63" currency: EUR in_stock: true reviews_count: 13 category: "Api" url: https://www.desertcart.pt/products/17923261-api-ph-down-freshwater-aquarium-water-ph-reducing-solution-4 store_origin: PT region: Portugal --- # Slow neutralization of alkaline substances Phosphate-free, safe for plants & fish 9.6% sulfuric acid for precise pH control API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle **Brand:** api **Price:** € 11.63 **Availability:** βœ… In Stock ## Summary > 🌊 Master your aquarium’s pH balance like a pro β€” because your fish deserve the best! ## Quick Answers - **What is this?** API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle by api - **How much does it cost?** € 11.63 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.pt](https://www.desertcart.pt/products/17923261-api-ph-down-freshwater-aquarium-water-ph-reducing-solution-4) ## Best For - api enthusiasts ## Why This Product - Trusted api brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - β€’ **Trusted Legacy:** Backed by 50+ years of API innovation, ensuring reliable, research-driven aquarium care. - β€’ **Precision pH Control:** Easily adjust aquarium pH with a potent 9.6% sulfuric acid formula for optimal fish health. - β€’ **Weekly pH Monitoring:** Use with API pH Test Kit to maintain perfect water balance and keep your tank thriving. - β€’ **Slow & Steady Adjustment:** Gradually neutralizes alkalinity to avoid shocking sensitive fish species. - β€’ **Plant & Fish Safe Formula:** Phosphate-free solution that prevents algae growth while protecting your aquatic ecosystem. ## Overview API pH DOWN is a 4-ounce freshwater aquarium solution designed to safely lower pH levels using a 9.6% sulfuric acid formula. Its phosphate-free composition prevents algae growth and protects both plants and fish. Ideal for weekly pH adjustments, it slowly neutralizes alkaline substances to maintain a stable, healthy aquatic environment. Trusted by aquarists for over 50 years, API ensures your freshwater community thrives with minimal effort. ## Description pH is the measure of acidity of water, on a scale ranging from 0 to 14. A pH of 0 is the most acidic, while a pH of 14 is the most alkaline. Different geographies have different tap water conditions with different pH levels, while fish require a specific pH level to thrive. A pH of 7.0 is ideal when keeping a community aquarium containing a variety of tropical fish. Goldfish and livebearers prefer a pH of 7.5. Many desertcartian fish, like angelfish and neon tetras, prefer a pH of 6.5 to 6.8. Mollies and swordtails thrive at pH 7.2 to 7.5. API pH DOWN Freshwater Aquarium Water pH Reducing Solution lowers aquarium pH in freshwater aquariums to desired level. Safe for fish and plants. Use when setting up a new aquarium, adjusting pH, or changing water. pH in an aquarium can fluctuate due to fish waste, uneaten food and addition of tap water. It is recommended to test water for pH weekly. With API Aquarium products, it’s easy to keep a beautiful saltwater, freshwater or reef aquarium. For over 50 years, API has been creating innovative, research-driven solutions that make it easier to care for your fish and aquarium. API Aquarium Treatment Supplies are designed to work in conjunction with each other to provide best results to control algae, promote healthy bacterial growth and help control and cure fish diseases and conditions such as ich and fin rot. They work to provide a safe, hospitable environment for fish such as tropical community fish, cichlids, goldfish and more. With API, you can spend more time admiring your fish, and less time scrubbing your tank. Make sure to use all products as directed in order to ensure the best results. Review: Works well lowering PH level - Does what it says, works well. It has no effects on my fish or plants. Review: Helps my fish tanks - Work good ## Features - Contains one (1) API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle - Lowers freshwater aquarium water pH with a phosphate-free formula - Does not promote algae growth with pH adjustments and is safe for plants and fish - Slowly neutralizes alkaline substances that cause high water pH - Test water weekly and use to correct pH level in freshwater aquariums - This product contains 9.6% of sulfuric acid ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B0002AQMV4 | | ASIN | B0002AQMV4 | | Best Sellers Rank | #7,738 in Pet Supplies ( See Top 100 in Pet Supplies ) #53 in Aquarium Water Treatments | | Brand Name | API | | Color | Multi | | Country of Origin | United States | | Customer Reviews | 4.6 4.6 out of 5 stars (2,958) | | Date First Available | June 15, 2004 | | Date First Available | June 15, 2004 | | Department | Unisex-Adult | | Department | Unisex-Adult | | Directions | Determine the pH of aquarium water with an API pH TEST KIT. To lower pH, add 2 drops per U.S. gallon (3.8 L) of aquarium water. Take another pH reading before adding another dose. Note that some fish may be sensitive to pH adjustments greater than .2 in a 24 hour period, so changes of this magnitude she be executed with extreme care. Use the API pH TEST KIT weekly to accurately monitor pH. Then, w… | | Is Discontinued By Manufacturer | No | | Item Dimensions LxWxH | 1.5 x 1.5 x 5.25 inches | | Item Package Dimensions L x W x H | 5.39 x 1.46 x 1.46 inches | | Item Weight | 0.3 Pounds | | Item model number | 30C | | Item model number | 30C | | Manufacturer | Mars Fishcare | | Manufacturer | Mars Fishcare | | Manufacturer recommended age | 1 month and up | | Material | Plastic | | Model Name | PH DOWN 4 OZ | | Number of Items | 1 | | Product Dimensions | 1.5 x 1.5 x 5.25 inches; 4.8 ounces | | Size | 4 oz | | Style | Down | | Target Audience Keyword | algae-eaters, betta-fish, bottom-feeder-fish, cichlid-fish, fish, goldfish, invertebrate-fish, mollusks, octopuses, rays, sharks, snails | ## Product Details - **Brand:** API - **Item Form:** Liquid - **Item Weight:** 0.3 Pounds - **Liquid Volume:** 118 Milliliters - **Manufacturer:** Mars Fishcare ## Images ![API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle - Image 1](https://m.media-amazon.com/images/I/71bFz9XJJBL.jpg) ## Available Options This product comes in different **Size, Style** options. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Works well lowering PH level *by M***R on December 12, 2025* Does what it says, works well. It has no effects on my fish or plants. ### ⭐⭐⭐⭐⭐ Helps my fish tanks *by P***H on December 20, 2025* Work good ### ⭐⭐⭐⭐⭐ Just as described *by L***. on December 29, 2025* Just as described. I use quite regularly as water coming out of my tap is pH 9 or higher. ## Frequently Bought Together - API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle - API AMMONIA 130-Test Freshwater and Saltwater Aquarium Water Test Kit --- ## Why Shop on Desertcart? - πŸ›’ **Trusted by 1.3+ Million Shoppers** β€” Serving international shoppers since 2016 - 🌍 **Shop Globally** β€” Access 737+ million products across 21 categories - πŸ’° **No Hidden Fees** β€” All customs, duties, and taxes included in the price - πŸ”„ **15-Day Free Returns** β€” Hassle-free returns (30 days for PRO members) - πŸ”’ **Secure Payments** β€” Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** β€” Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.pt/products/17923261-api-ph-down-freshwater-aquarium-water-ph-reducing-solution-4](https://www.desertcart.pt/products/17923261-api-ph-down-freshwater-aquarium-water-ph-reducing-solution-4) --- *Product available on Desertcart Portugal* *Store origin: PT* *Last updated: 2026-04-25*