★★★★★
Works well lowering PH level
Megrier—December 12, 2025✓ Verified purchase
Does what it says, works well. It has no effects on my fish or plants. Read more
API
API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle
$5.88$8.38
About this item
- 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
$5.88
Was $8.38Save $2.50
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Product details
| Brand | API |
|---|---|
| Liquid Volume | 118 Milliliters |
| Item Weight | 4.8 ounces |
| Item Form | Liquid |
| Manufacturer | Mars Fishcare |
Technical specifications
| item_weight | 4.8 ounces |
|---|---|
| department | Unisex-Adult |
| manufacturer | Mars Fishcare |
| item_model_number | 30C |
| date_first_available | June 15, 2004 |
| item_package_dimensions_l_x_w_x_h | 5.4 x 1.5 x 1.5 inches |
| item_dimensions_lxwxh | 1.5 x 1.5 x 5.25 inches |
| brand_name | API |
| target_audience_keyword | algae-eaters, betta-fish, bottom-feeder-fish, cichlid-fish, fish, goldfish, invertebrate-fish, mollusks, octopuses, rays, sharks, snails |
| 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, when necessary, use pH DOWN to reduce pH levels in your aquarium. Tip: Some water is high in mineral ions, such as carbonate and bicarbonate, which strongly buffer aquarium water and can resist a pH change or cause “pH rebound.” In these situations, repeated dosing may be necessary to lower pH. |
| country_of_origin | United States |
| model_name | PH DOWN 4 OZ |
| color | Multi |
| size | 4 oz |
| material | Plastic |
| number_of_items | 1 |
| style | Down |
| is_discontinued_by_manufacturer | No |
| product_dimensions | 1.5 x 1.5 x 5.25 inches; 4.8 ounces |
| manufacturer_recommended_age | 1 month and up |
| best_sellers_rank | #7,536 in Pet Supplies ( See Top 100 in Pet Supplies ) #49 in Aquarium Water Treatments |
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Customer reviews
4.62,967 ratings
- 5★75%
- 4★13%
- 3★13%
- 2★0%
- 1★0%
Customers say
Customers find the pH adjusterer works well, particularly for 30-gallon tropical fish tanks, and appreciate its quality and value for money.
★★★★★
Helps my fish tanks
Patrick H—December 20, 2025✓ Verified purchase
Work good Read more
★★★★★
Just as described
Lisa M.—December 29, 2025✓ Verified purchase
Just as described. I use quite regularly as water coming out of my tap is pH 9 or higher. Read more
★★★★☆
Good stuff
D.—June 12, 2025✓ Verified purchase
It does a good, adequately changes pH and does it fast. It's easy to add to the water, just use the measuring cup in the cap. Use a test strip before and after and you should see the difference. I have a large aquatic turtle in a 300 gallon indoor pond and this product couldn't keep up with that long-term. What it did do was give me a safe way to treat the water for pH, temporarily, while I got an appropriate system in place. It's a good price for that kind of snappy resolution. Thank you! Read more
★★★★★
Great product
Woman in TN—July 2, 2025✓ Verified purchase
Easy to order, received without issues in good condition and does wonders for fish tank. Read more
★★★★★
Easy to use for aquarium fish
Stephanie F—June 21, 2025✓ Verified purchase
Works just as advertised. Easy to use but you do need to have a ph testing kit to verify desired ph level. Read more
★★★★★
Stabilize your water with this product!
Krishna—April 10, 2025✓ Verified purchase
If you are having a plan to properly setup a new big size aquarium or even water change, this is a good recommendation. Our pH was more than 8 when tested with pH aquarium test kit. Would recommend to follow the instructions correctly, particularly not to use too much within a day to stress the fishes. Water clarity is pretty good. Fishes were able to adapt this change & I see them performing healthier. Overall good product for money & easy to use. Read more
★★★☆☆
Worked with one tank but not the other
Melody—September 2, 2021✓ Verified purchase
I was so excited to receive this so I could stop worrying about the high PH in both of my fish tanks until my almond leaves came in. It worked very well for my 5 Gallon tank but sadly, it made no difference in my 20 gallon :( i listened to the instructions, I’ve done more frequent water changes, I’ve put more than the recommended amount (there’s no fish inside!) and nothing has been working :( guess I just have to keep waiting for my almond leaves! Read more
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