Fluval Cycle Biological Enhancer, Aquarium Water Treatment, 16.9 Oz., A8351

Started a 55 gallon aquarium with it. I have good water parameters with the three tiger barbs as the only members, One thing I would stress is to shake well before using. The label gives directions for starting aquariums and when the biological filter is stressed.

Had been trying to fishless cycle a tank for several weeks. We had tried similar products from other companies and had zero results. This was a last ditch buy and didn’t expect any results. I did the three day dosing and on the third day I had 2 ppm ammonia and 0 nitrates. 3 days later the ammonia has dropped to .5 ppm and nitrates are at 10 ppm. I had pretty much assumed all of these products were snake oil but this actually got some bacteria going.

Great product for cyclists and keeping water parameters pristine

Easy to use. Just pour it in without mixing

Works great for a biological enhancement

I set up a new 10 gallon tank with new filter and media. Added 6 medium size tiger barbs and dosed with Cycle as directed for first three days--and then occasionally afterwards. Tested water daily and zero ammonia and nitrite always. Nitrate began appearing shortly after--indicating the cycle was becoming established. The product works, but be reasonable in the amount of fish you add at first. Frequent water testing is a must when starting a new tank--with or without a bacteria booster.

Great product works as promised

We were having trouble with high Nitrite levels. I was doing water changes every two days. Ammonia levels were at Oppm but Nitrites were high. I tried using two other products that were a waste of time. Nothing was working to bring the Nitrites down for good. Until I used this. I put the recommended dosage and 24 hours later Nitrites were at 0ppm. Amazing product. The bottle was much larger than I figured. Thanks Fluval

This product has proven itself for me twice now. First, I had a new 40 gallon aquarium and was performing a fishless cycle. I always use a lot of filter capacity in my tanks. This one was taking forever to cycle - it had been about a month and was still not processing ammonia. Ammonia concentration was constant, and no nitrites or nitrates at all. I ran out of patience and bought some Fluval Cycle. I followed the instructions, and the very next day I had zero ammonia. More amazing, I had zero nitrites but nitrates were present. I had gone right past the nitrite spike and fully cycled. I added some more ammonia, which was processed by the next day. I did my partial water change and added fish. Parameters have been perfect ever since. More recently, I had an immediate need for a quarantine tank for some new fish. I set up a brand new tank, added the Fluval Cycle, and added the fish (just four fish in a 20 gallon aquarium). The next day I had zero ammonia, zero nitrites and a trace of nitrates. From there, nitrates increased as expected, but I never saw a glimpse of ammonia or nitrites. My tank had instantly cycled. To be clear, I had a low stocking level and plenty of filter capacity. Even so, I have never seen this before. In the future, whenever I need to start up a tank I will use this product. I will add it then add some fish to the new tank immediately, bringing up stocking level over time. I have had many aquariums and garden ponds over the years, and havent seen anything like this before.

Fiances tank crashed after a fish died. His ammonia was very high and his bacteria couldnt keep up. To save the tank I took a filter from my established tank and added it to his hang on back filter next to his filter pad and added the fluval bacteria directly to the filter. 2nd day his ammonia was gone and nitrogen cycle was back to normal. I will keep one or these around in case of emergency.