---
product_id: 49040210
title: "Cycle Biological Enhancer, 250 ml ( Packaging may vary)"
brand: "fluval"
price: "4112 kr"
currency: ISK
in_stock: true
reviews_count: 13
category: "Fluval"
url: https://www.desertcart.is/products/49040210-cycle-biological-enhancer-250-ml-packaging-may-vary
store_origin: IS
region: Iceland
---

# Safe for plants, fish & humans Instant beneficial bacteria boost Eliminates toxic ammonia & nitrites Cycle Biological Enhancer, 250 ml ( Packaging may vary)

**Brand:** fluval
**Price:** 4112 kr
**Availability:** ✅ In Stock

## Summary

> 🧪 Transform your tank into a thriving aquatic paradise—because your fish deserve the best!

## Quick Answers

- **What is this?** Cycle Biological Enhancer, 250 ml ( Packaging may vary) by fluval
- **How much does it cost?** 4112 kr with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.is](https://www.desertcart.is/products/49040210-cycle-biological-enhancer-250-ml-packaging-may-vary)

## Best For

- fluval enthusiasts

## Why This Product

- Trusted fluval brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Eco-Friendly & Safe:** Formulated to protect your plants, aquatic animals, and even you—no compromises.
- • **Effortless Maintenance:** Use regularly to outcompete harmful bacteria and maintain crystal-clear, balanced water.
- • **Toxic-Free Water, Happy Fish:** Effectively neutralizes harmful ammonia and nitrites to keep your fish stress-free and vibrant.
- • **Trusted by Aquarists Worldwide:** Top-ranked biological enhancer with thousands of 5-star reviews backing your aquarium’s success.
- • **Jumpstart Your Aquarium's Health:** Powerful bacterial blend kickstarts a thriving aquatic ecosystem from day one.

## Overview

Fluval Cycle Biological Enhancer is a 250ml liquid supplement designed to rapidly establish beneficial bacteria in new and existing aquariums. It safely eliminates toxic ammonia and nitrites, creating a balanced biological environment that supports healthy fish and plants. Trusted globally, this product simplifies aquarium startup and ongoing maintenance, ensuring crystal-clear water and vibrant aquatic life.

## Description

Product Description Fluval Cycle biological aquarium supplement for new tank startups and regular maintenance 250ml. Directions The product_description from the external source provides the following instructions: 1. Use Fluval Cycle Biological Enhancer for new aquariums to establish safe and essential conditions. 2. Apply the product regularly to competitively exclude undesirable bacteria in aquariums. 3. Add the product to aquarium water to eliminate toxic ammonia and nitrites, creating a biologically well-balanced aquarium for healthy fish to thrive. P.when('A').execute(function(A) { A.on('a:expander:toggle_description:toggle:collapse', function(data) { window.scroll(0, data.expander.$expander[0].offsetTop-100); }); }); Box Contains Cycle See more

Review: Maintain a healthy Aquarium - I use this product when setting up a new aquarium (as part of the nitrogen cycle to promote healthy ammonia eating bacteria growth, a 6 to 8 week process) and as part of my weekly water changes. I feel that this product works very well, as my fish are all happy and healthy and I have never experienced any bad water quality issues (ammonia spikes etc). I use this weekly to add to my 200ltr, 60ltr and 30ltr aquariums when I do a water change. I change 20% - 30% of the water volume and add an appropriate dose of this stuff, however it's not really possible to overdose so it does not really matter if you add a little bit extra. I usually do add a bit more than stated on the label. I keep it stored at room temperature and the 2ltr bottle usually lasts me about 6 weeks. There is always a seal covering the opening after the lid has been unscrewed, so you know it is brand new and has not been opened / tampered with. This is safe for my fresh water aquarium inhabitants, of which I have many varieties. Pros: - The larger 2ltr bottle is excellent value compared to the 250ml or 500ml bottles - Quick delivery / repeat orders available - Far cheaper than my local pet store Cons: - Nothing I can think of really I hope this review has been helpful to you. Happy Fish Keeping!
Review: Used for years.great product. - Does what it says.

## Features

- Powerful team of beneficial bacteria immediately inoculates aquarium water
- Creates a safe biological habitat for your fish
- Eliminates ammonia and nitrite
- Will not harm plants; animals or humans
- Size: 8.4 oz.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B00FPIZ8Y0 |
| Best Sellers Rank | 529 in Pet Supplies ( See Top 100 in Pet Supplies ) 3 in Aquarium Water Treatments |
| Brand Name | Fluval |
| Country Of Origin | United Kingdom |
| Customer Reviews | 4.6 4.6 out of 5 stars (6,634) |
| Global Trade Identification Number | 00015561183499 |
| Item Form | Liquid |
| Item Type Name | Cycle Biological Aquarium water treatment |
| Item Weight | 8.45 Ounces |
| Liquid Volume | 8.4 Fluid Ounces |
| Manufacturer | Rolf C Hagen UK Ltd |
| Manufacturer Part Number | A8349 |
| Model Number | A8349 |
| Target Species | Fish |
| UPC | 015561183499 |
| Unit Count | 1 Count |

## Product Details

- **Brand:** Fluval
- **Item form:** Liquid
- **Item weight:** 8.45 Ounces
- **Liquid volume:** 8.4 Fluid Ounces
- **Manufacturer:** Rolf C Hagen UK Ltd

## Images

![Cycle Biological Enhancer, 250 ml ( Packaging may vary) - Image 1](https://m.media-amazon.com/images/I/71CbLgtkAbL.jpg)

## Questions & Answers

**Q: i have a 240l tank how much cycle do i use in my tank it is a new tank.**
A: Tip the whole bottle in your filter

**Q: Can this be used to boost some established bio media in a new tank?**
A: Yes definately. Put it in the tank as instructions say. Then keep putting a min og 10 ml in until your happy. I used it for setting up new 200 ltr tank and it's the only stuff I used after that.

**Q: Can I use this in salt water?**
A: Having read the information on the back of the bottle it says that it is safe for use in fresh and salt water aquariums.

**Q: I want to add new fish into my established tank. Can I add this into the tank, let the bag with new fish float for a while then release the fish?**
A: No! What you must do is add this after following the instructions and leave for a few days for the bacteria to establish a proper environment for the fish before they are added. Try reading a book or 3 on setting up a fish tank.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Maintain a healthy Aquarium
*by M***D on 3 April 2021*

I use this product when setting up a new aquarium (as part of the nitrogen cycle to promote healthy ammonia eating bacteria growth, a 6 to 8 week process) and as part of my weekly water changes. I feel that this product works very well, as my fish are all happy and healthy and I have never experienced any bad water quality issues (ammonia spikes etc). I use this weekly to add to my 200ltr, 60ltr and 30ltr aquariums when I do a water change. I change 20% - 30% of the water volume and add an appropriate dose of this stuff, however it's not really possible to overdose so it does not really matter if you add a little bit extra. I usually do add a bit more than stated on the label. I keep it stored at room temperature and the 2ltr bottle usually lasts me about 6 weeks. There is always a seal covering the opening after the lid has been unscrewed, so you know it is brand new and has not been opened / tampered with. This is safe for my fresh water aquarium inhabitants, of which I have many varieties. Pros: - The larger 2ltr bottle is excellent value compared to the 250ml or 500ml bottles - Quick delivery / repeat orders available - Far cheaper than my local pet store Cons: - Nothing I can think of really I hope this review has been helpful to you. Happy Fish Keeping!

### ⭐⭐⭐⭐⭐ Used for years.great product.
*by J***N on 19 November 2025*

Does what it says.

### ⭐⭐⭐⭐⭐ Good
*by P***L on 3 May 2025*

Does exactly as it says on the tin or bottle!!! Definitely a must have for the health of your fish to get the chlorine out of tap water and help control ammonia.

## Frequently Bought Together

- Fluval Cycle Biological Enhancer, Aquarium Water Treatment, 8.4 Oz., A8349
- Fluval Waste Control Biological Cleaner, Aquarium Water Treatment, 8.4 Oz., A8355
- Fluval Clarify Bio for Aquarium Water Treatment, 4-Ounce

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*Product available on Desertcart Iceland*
*Store origin: IS*
*Last updated: 2026-04-28*