Fluval Cycle Biological Booster Water Conditioner, 8.4-fl oz bottle

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About This Item

Details

  • Allows for the immediate addition of fish to a new freshwater or saltwater aquarium. Rapidly establishes a safe biological aquarium environment and metabolizes dangerous fish waste
  • Prevents loss of fish, reduces aquarium maintenance, and removes organic matter that can cause toxic levels of ammonia, nitrate,and other pollutants. Digests waste in filters, gravel and surfaces.
  • Safe for plants, animals or humans. No refrigeration required. Appropriate for both fresh and saltwater environments
  • Bio-floc technology ensures product stability, efficacy and shelf life
  • Every container contains pure, safe bacterial colonies, free of undesirable contaminants

Instructions

FAQ

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Questions & Answers

8 Customer Questions

I was told to use this to get the nitrite to go down in tank along with API Nitra-Zorb. I have had my tank for 10 weeks. Everything other than nitrites are fine but Nitrites are at 0.5. What else do I do. I have done a 25 percent water change

Can I add more than "required" while the tank is cycling (no fish), then use it for a month before adding fish? Thanks!

Answer by Chewy • Dec 17, 2018
We recommend using the manufacturer's suggestion. New aquariums will use this for three days in a row. On day 1, you'll use 25 milliliters per every 10 gallons. On day 2, you'll use 10 milliliters for every 10 gallons. On day 3, you'll use 10 milliliters per every 10 gallons. If you've added fish, you'll use 10 milliliters for every 10 gallons. If used for weekly dosage for regular maintenance activities and to maintain a strong beneficial biological colony, you'll use 5 milliliters for every 10 gallons.

Can I use this product in a turtle tank

Answer by Chewy • Mar 29, 2022
This water conditioner is formulated for Tropical Freshwater and Marine Fish.

What's the difference between Fluval Biological Booster, Cleaner, and Enhancer? They seem like the same exact thing?

Answer by Chewy • Oct 26, 2018
The Fluval Biological Booster allows for the immediate addition of fish to a new freshwater or saltwater aquarium. The Fluval Biological Enhancer quickly reduces organic waste and makes your aquarium maintenance easier.
Reviews
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4.6
Rated 4.6 out of 5 stars
66 Ratings
Terms & Conditions

26 Customer Reviews

Rated 5 out of 5 stars
By Alfred on Jan 28, 2026

Helps keep water clear

Clear water and happy fish.... what more could you ask for?

Clear water and happy fish.... what more could you ask for?

Rated 5 out of 5 stars
By Bryan on Aug 11, 2025

Yes!

I used this and saw a very fast change for the better in both my big tanks! I have senince order 4 at a time. Love it water went glassy clear fish became more active

I used this and saw a very fast change for the better in both my big tanks! I have senince order 4 at a time. Love it water went glassy clear fish became more active and happy. I know when my fish are happy believe it or not! Love it!

Rated 5 out of 5 stars
By Joan on Oct 8, 2025

I use this every time I do a water change

This makes such a huge difference after a water change. I definitely recommend it!

This makes such a huge difference after a water change. I definitely recommend it!

Rated 5 out of 5 stars
By Margaret on Jun 17, 2025

I have used these items for years and have had good resullts.

Keeps my fish healthy.

Keeps my fish healthy.

Rated 5 out of 5 stars
By Carol on Nov 13, 2024

water conditioner

it works well

it works well

Rated 2 out of 5 stars
By Destiny on Jan 1, 2024

Doesn't treat up to 240 gallons

I'm not sure if it works. I was only able to dose for day 1 & 2. I completely ran out of the product and wasn't able to dose on day 3. I read that the 4oz bottle

I'm not sure if it works. I was only able to dose for day 1 & 2. I completely ran out of the product and wasn't able to dose on day 3. I read that the 4oz bottle dosed up to 240 gallons. My tank is only 40 gallons...

Rated 5 out of 5 stars
By apeflames on Dec 12, 2023

Bang for your buck

They were out of the Bio I usually buy so I got this. It is way more concentrated, and you can treat 1000 gallons with one bottle of this. Double what the other

They were out of the Bio I usually buy so I got this. It is way more concentrated, and you can treat 1000 gallons with one bottle of this. Double what the other brand does. I use this with every water change. Never have cloudy water.

Rated 4 out of 5 stars
By Susan on Nov 25, 2023

Cloudy tank hoping this clears it

A few applications still trying for better results

A few applications still trying for better results

Rated 2 out of 5 stars
By Shelly on Feb 17, 2022

Fluval Cycle bacteria booster

Though this product contains nitrifying bacteria, it does not contain the ones that develop naturally, Nitrosomonas species and Nitrobacter species. Do your

Though this product contains nitrifying bacteria, it does not contain the ones that develop naturally, Nitrosomonas species and Nitrobacter species. Do your research so you won’t make the same mistake, otherwise, with Fluval, you’ll have to always add it because the bacteria will keep dying off and not establish themselves in your tank

Rated 5 out of 5 stars
By Barb on Dec 19, 2021

Fuval Cycle

I have used Fuval Cycle biological booster for several years. It works well and I add it to new tanks. I also add it after every water change. I was glad to see

I have used Fuval Cycle biological booster for several years. It works well and I add it to new tanks. I also add it after every water change. I was glad to see the larger size on Chewy.