QUICK START Freshwater and Saltwater Aquarium Nitrifying Bacteria 16-Ounce Bottle

I’ve been keeping freshwater fish tanks for five years now I do use API a lot more than some other companies because for my needs it does a great job. You can rely on a PI to deliver, and if there is any problem, you can contact the company they have pretty good Customer service. They too are enthusiasts in the hobby and also lifestyle, but they also understand that sometimes things go wrong. In my opinion, API is a great company. I would love to do some YouTube videos and maybe they would sponsor me.

Works as advertised, arrived quickly and damage free. Will purchase again

Works great

Must have for any fish tank owner! Great product and good bottle size for the price. This is my first refill - the first bottle lasted me nearly two years.

Good product with cheap price

Have used Quick Start on two tanks now, one 10 gallon and one 45 gallon. The product works, BUT it has to be used in the right way (which isn't the one printed on the back label.) The first time I used it on the 10 gallon was my first time setting up an aquarium, and I pretty much just dumped the recommended dosage in along with conditioner/stress zyme, then put in fish the next day. After about a week or two my ammonia levels spiked hard, then another one to two weeks or so after that my nitrites and nitrates started to spike. Ended up losing 50% of my fish before the cycle finally stabilized (the remainder have survived over a year now). The problem is that the cycle needs ammonia to start, and a brand new tank will not have any, nor does Quick Start contain ammonia. Therefore, if you just dump it into a new tank, then put in fish, the cycle will not start until the fish food/waste starts to decompose into ammonia, which can take a week or more. Once sufficient ammonia is present in the tank (3-5ppm), it takes about another week or two for the bacteria to then break it down to nitrites and then nitrates, completing the cycle. During this time your fish will be suffering high ammonia and nitrite levels, even with frequent water changes. To properly cycle your tank with Quick Start, you need to introduce ammonia into the water quickly and without fish. The "natural" and slower way to do this is to put biomass into the tank and wait for it to rot. This can be store bought fish (not live), shrimp, fish pellets/flakes, etc. However, these take time to decay. The faster way to introduce ammonia is to directly buy a bottle of liquid ammonia designed for cycling aquariums, and put in enough to reach 4-5ppm. Then immediately add API Quick Start, along with any conditioner/etc. After about a week or so you'll notice the ammonia levels go down, and nitrites start spiking. After another few days the nitrites and ammonia will both go down close to or at 0, and nitrates will be present. Now the tank is fully cycled, and it's safe to add fish.

The API QUICK START for freshwater and saltwater aquariums is a total game-changer—especially if you're setting up a new tank or adding fish to an existing one. It makes the nitrogen cycle process way less stressful, both for you and your fish. I used it when starting a new freshwater setup, and within 24 hours my tank was safe and stable. No ammonia spikes, no nitrite issues—it genuinely helps establish the biological filter FAST. It's also great to use after water changes, adding new fish, or cleaning the filter. What I love is that it’s super easy to use—just shake and pour. The bottle gives clear instructions, and the results speak for themselves. My fish were active and healthy from day one. This is one of those products you always want on hand. It helps create a healthy environment and gives peace of mind whether you're a beginner or a seasoned aquarist.

Last year I made the conversion to planted tanks and ever since then, I have been battling cyanobacteria in my 75 gallon tank. Ammonia, nitrites, and nitrates were always great, but within 1-2 days of an extremely thorough tank maintenance session (1-2 hours of cleaning plants, wood, walls, rocks + water change), the cyanobacteria population would explode. If I didn't address it right away, the plants, substrate, walls, heater, and filter would be covered in sheets of cyanobacteria. Take maintenance every 1-2 days was not very sustainable. I tried feeding less, feeding flakes vs crisps vs round pellets. Some types of food exacerbated the issue. Pellets and the premium gel food helped combat the growth of cyanobacteria but I still had to do tank maintenance every 3-4 days. I tried completely resetting the tank using the existing plants (cleaned) and swapping wood for rocks. I tried adding $300 worth of plants, in addition to what was already planted. I tried moving plants and decor around for optimal water flow so there weren't any dead spots. I tried moving from a canister filter to an external filter. Then I upgraded to a higher capacity external filter to get better water flow in the tank. I tried treating the tank with different products, specifically formulated to address the cyanobacteria and although it would keep it at bay, once you stopped using the product, the cyanobacteria would be back in full force. All of this was expensive and futile because the cyanobacteria always returned with a vengeance. Of course, no one could give me a definitive answer to the cyanobacteria problem. I scoured article after article, frustrated that I couldn't find a solution that actually worked. And believe me, I spent $1000+ over the year trying a number of different solutions; none of them worked permanently. I was seriously rethinking my fish hobby when I stumbled across the solution. I picked up Quick Start for another tank that I wanted to rebuild. I happened to be doing a water change for my 75 gallon tank at the same time and I accidentally put Quick Start in my 75 gallon tank. No biggie, I thought. Wouldn't hurt and I didn't want to waste the water. In two days, I noticed that the cyanobacteria's growth had been stunted. It was growing about half the speed it normally did. The next water change, I used Quick Start again. I didn't understand - my levels were good when I tested them so I didn't think my bacteria levels were low and I never thought to use Quick Start as a result. Over the next few weeks, I kept using Quick Start in my water changes, I got a bunch of snails (freeloaders from my plant purchases), and I stopped vacuuming the substrate so thoroughly and now the cyanobacteria is 95-98% gone. I only occasionally see it on the walls and I can push my water changes to every two weeks, no problem. I think I owe my sanity to Quick Start.