--- product_id: 497951650 title: "MicroBacterStart XLF - 15X Concentrated Live Tank Starter for Cycling New Freshwater Aquarium and Establishing Nitrifying Bacteria" brand: "brightwell aquatics" price: "€ 36.43" currency: EUR in_stock: true reviews_count: 5 category: "Brightwell Aquatics" url: https://www.desertcart.hr/products/497951650-microbacterstart-xlf-15x-concentrated-live-tank-starter-for-cycling-new store_origin: HR region: Croatia --- # 15X concentrated live microbes Cycles tank in 5-7 days Prevents New Tank Syndrome MicroBacterStart XLF - 15X Concentrated Live Tank Starter for Cycling New Freshwater Aquarium and Establishing Nitrifying Bacteria **Brand:** brightwell aquatics **Price:** € 36.43 **Availability:** ✅ In Stock ## Summary > 🚀 Fast-track your aquarium’s health with MicroBacterStart XLF – because your fish deserve the best! ## Quick Answers - **What is this?** MicroBacterStart XLF - 15X Concentrated Live Tank Starter for Cycling New Freshwater Aquarium and Establishing Nitrifying Bacteria by brightwell aquatics - **How much does it cost?** € 36.43 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/497951650-microbacterstart-xlf-15x-concentrated-live-tank-starter-for-cycling-new) ## Best For - brightwell aquatics enthusiasts ## Why This Product - Trusted brightwell aquatics brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - • **Rapid 5-7 Day Cycle:** Say goodbye to waiting—establish a stable nitrogen cycle faster than ever. - • **High-Density Tank Ready:** Perfect for heavily stocked aquariums and new fish introductions without stress. - • **Long-Lasting Proprietary Base:** Formulated for maximum microbial longevity, ensuring consistent performance. - • **Emergency Nitrification Rescue:** Instantly restore nitrifying bacteria after tank cleanings or medication use. - • **Supercharged 15X Concentration:** Turbocharge your aquarium’s biological filtration with a potent, live microbial blend. ## Overview MicroBacterStart XLF is a 15X concentrated live bacterial suspension designed to rapidly establish and maintain biological filtration in freshwater aquariums. It accelerates the nitrogen cycle, preventing toxic ammonia and nitrite spikes within 5-7 days, making it ideal for new setups, high-density tanks, and post-cleaning recovery. Supplied in a proprietary base for enhanced longevity, this American-made formula supports a thriving aquatic environment with scientifically backed efficacy. ## Description Brightwell Aquatics MicroBacter Start XLF Experience a new level of aquarium care with Brightwell Aquatics MicroBacter Start XLF – the ultimate solution for achieving a balanced and thriving aquatic environment. Our concentrated formula is designed to boost the nitrogen cycle in your aquarium, ensuring the rapid establishment of biological filtration and creating a stable habitat for your aquatic companions. It’s particularly useful for new startups, resulting in tank cycling in 5 to 7 days in most cases. This shrimp safe advanced blend works effectively to break down organic waste, keeping your aquarium water pristine. It is meticulously formulated to enhance water quality and eliminate ammonia and nitrite spikes. Whether you're setting up a new tank or maintaining an established one, MicroBacter Start XLF is your go-to solution. Its versatility extends to fish and invertebrate freshwater aquariums and is particularly effective for live planted aquariums, providing powerful support for a diverse range of aquatic environments. FEATURES AT A GLANCE Super concentrated 15x strength formula Useful for rapidly re-establishing nitrification bacteria in case of an emergency Usually cycles in 5-7 days Ideal in aquaria with high population densities and when adding new fish Best used post-cleaning of rocks and surfaces or after use of medication Prevents “New Tank Syndrome” Supplied in a proprietary base for maximum longevity Formulated utilizing extensive data compiled by microbiologists AMERICAN-MADE EXCELLENCE Trust in the quality and excellence of Brightwell Aquatics, an industry-leading brand committed to providing innovative and scientifically backed aquatic care products. Made in the USA, we consistently strive to deliver advanced superior quality solutions to elevate the vibrancy and health of your aquarium. Review: Amazing product!! My tank was cycling for over a month and no changes, my ammonia 0ppm, nitrite super high and barely any nitrate, and I was using brightwell florin bacter 7 which is great as well but for some reason wasn’t working for this bigger tank. So I did some research and it said I could just substitute the florin Bacter for the micro bacter start XLF since they’re the same brand and are compatible (do your research) so I did and after 4 days dosing it my tank was ready and no nitrites at all!! It was like magic. I recommend this to start cycling the tank since it’s so strong and then continue after water changes with the Florin Bacter7 which is what I’m doing and it’s going great so far. Also keep both in the fridge. One think I must add is that for some reason I thought the bottle was going to be bigger because of the picture they display but it’s still enough because it’s concentrated and it’s only to use once in a while. I also use it when I have ammonia in my nano tank I dose it for 2-3 days and it boosts the nitrifying bacteria 🙌🏻 love it and will buy again and again. Review: I’ve had very good results using Brightwell Aquatics MicroBacter alongside cycled or seeded bio media. Using both together really helps fast track the cycling process instead of starting from zero. It’s easy to dose and has been especially helpful when setting up new tanks or reinforcing an existing cycle after changes. Pairing it with established media has made cycling much quicker and less stressful. I like keeping it on hand for both new setups and ongoing tank maintenance. ## Features - Concentrated 15X Suspension of LIVE non-pathogenic microbes, specifically formulated to extremely rapidly establish biological filtration in new aquarium set-ups, and to enhance the rate of nitrification in existing systems. - Useful for rapidly re-establishing nitrification bacteria in case of an emergency - Particularly useful in aquaria with high population densities and when adding new fish. Supplied in a proprietary base which provides for maximum longevity. - Helpful to re-establish nitrifying bacteria after cleaning rocks and surfaces and after use of medications. 1. Rapid reduction of ammonia, and nitrite. 2. Prevents “New Tank Syndrome.” - Takes 5-7 days to cycle. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B086Z6VTJW | | Best Sellers Rank | #41,898 in Pet Supplies ( See Top 100 in Pet Supplies ) #357 in Fish Medication & Health Supplies | | Customer Reviews | 4.5 4.5 out of 5 stars (1,105) | | Date First Available | 6 October 2022 | | Item Form | Liquid | | Item Weight | 141 g | | Item model number | BACSTARTXLF125 | | Package Dimensions | 12.19 x 3.91 x 3.71 cm; 140.89 g | | Quantity | 1 | | Size | 125-ml | | batteries required | No | ## Product Details - **Brand:** Brightwell Aquatics - **Item form:** Liquid - **Item weight:** 4.97 Ounces - **Liquid volume:** 125 Milliliters - **Manufacturer:** Brightwell Aquatics ## Images ![MicroBacterStart XLF - 15X Concentrated Live Tank Starter for Cycling New Freshwater Aquarium and Establishing Nitrifying Bacteria - Image 1](https://m.media-amazon.com/images/I/611mZuJRXKL.jpg) ## Available Options This product comes in different **Size** options. ## Questions & Answers **Q: I had a major nitrite and nitrate spike. crazy high. my ph was super low, probably the only reason my beta survived. how long will this take to work?** A: I'm sorry but the person who said it would cycle in 2 days is absolutely wrong. Scientifically that cannot and will not happen. If you educate yourself on the nitogen cycle you will see why. You are right about your ph being super low and your beta surving because the lower your ph is; less toxic form or ammonium will be present than the more toxic ammonia. **Q: How long does the water stay cloudy after use?** A: Once the bacteria begins to bloom , the cloudiness could last a couple weeks . API accu-clear will clear up the cloudiness without affecting the cycle. **Q: I have nitrogen spikes in my aquarium sometimes after my water changes. Would using this in replacement water be a reasonable preventative or waste $?** A: This product is hardly a waste of money , I use it in replacement water after every monthly gravel vac to prevent (new water syndrome). My fish seem to instantly detect its presense quicker than Seachems Stability. Nitrogen prevention , however isn't exactly what this product is for. Yes true , beneficial bacteria products help convert ammonia into nitrite , and then nitrite into harmless nitrate. But the cycle time in which this occurs takes many weeks of patience. If your filter is already cycled , it still takes many days to go through the conversion process. Therefore during a nitrogen spike , you would be better off purchasing Seachems Safe (and be prepared for the white powder substance to smell like sulfur) , this is normal and the answer to your nitrogen problem. **Q: When it says remove "filter floss" what exactly does it mean?** A: That means take the filter cartridges out of your filter ........ In other words run it without the carbonated screens that you put in. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Review *by G***️ on 5 December 2025* Amazing product!! My tank was cycling for over a month and no changes, my ammonia 0ppm, nitrite super high and barely any nitrate, and I was using brightwell florin bacter 7 which is great as well but for some reason wasn’t working for this bigger tank. So I did some research and it said I could just substitute the florin Bacter for the micro bacter start XLF since they’re the same brand and are compatible (do your research) so I did and after 4 days dosing it my tank was ready and no nitrites at all!! It was like magic. I recommend this to start cycling the tank since it’s so strong and then continue after water changes with the Florin Bacter7 which is what I’m doing and it’s going great so far. Also keep both in the fridge. One think I must add is that for some reason I thought the bottle was going to be bigger because of the picture they display but it’s still enough because it’s concentrated and it’s only to use once in a while. I also use it when I have ammonia in my nano tank I dose it for 2-3 days and it boosts the nitrifying bacteria 🙌🏻 love it and will buy again and again. ### ⭐⭐⭐⭐⭐ Review *by B***E on 17 February 2026* I’ve had very good results using Brightwell Aquatics MicroBacter alongside cycled or seeded bio media. Using both together really helps fast track the cycling process instead of starting from zero. It’s easy to dose and has been especially helpful when setting up new tanks or reinforcing an existing cycle after changes. Pairing it with established media has made cycling much quicker and less stressful. I like keeping it on hand for both new setups and ongoing tank maintenance. ### ⭐⭐⭐⭐⭐ Review *by C***D on 7 April 2026* I have always used Fritz bacteria but once I tried this little bottle, there was no going back. I was emergency in cycling a tank and struggling so bad. Had gone through a ton of Fritz and many weeks, but one does of this and my parameters were moving in the right direction 24 hrs later and nearly cycled within 72 hrs. It’s a smaller bottle but the doses are smaller so don’t let that deter you. My tiny bottle has lasted me almost a year now and I just started cycling a new tank with it and have nitrite on day 3! I swear by it! Save yourself time, money and headache and just buy it! ## Frequently Bought Together - Brightwell Aquatics MicroBacter Start XLF - Concentrated Freshwater Nitrifying Bacteria - Quick Start Fish Tank Starter, Lift Microbe Levels & Water Filtering - Aquarium Water Treatments, 4.22 fl oz - API TAP WATER CONDITIONER Aquarium Water Conditioner 16-Ounce Bottle - API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, White, Single, Multi-colored --- ## Why Shop on Desertcart? - 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016 - 🌍 **Shop Globally** — Access 737+ million products across 21 categories - 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price - 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members) - 🔒 **Secure Payments** — Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.hr/products/497951650-microbacterstart-xlf-15x-concentrated-live-tank-starter-for-cycling-new](https://www.desertcart.hr/products/497951650-microbacterstart-xlf-15x-concentrated-live-tank-starter-for-cycling-new) --- *Product available on Desertcart Croatia* *Store origin: HR* *Last updated: 2026-05-15*