MicrōBacter Start XLM 

Professional 15x strength powerful live tank starter nitrifying bioculture, with much fewer temperature and shelf life restrictions than competing products, for rapidly cycling new marine fish and reef aquaria and brackish aquariums, and for recovering from overcrowding or disasters where the bacteria bed has been damaged or when adding new fish.  It is also quite useful after re-arranging decorations or performing major maintenance, such as cleaning substrates or biological media to "recharge" the nitrifying bacteria population.


  • Super 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
  • 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.”
  • Supplied in a proprietary base which provides for maximum longevity
  • Formulated utilizing extensive data compiled by microbiologists.


125ml | 250ml | 500ml | 2L | 1 L | 2L | 4 L | 20L




MicrōBacter Start XLM 15X creates a nitrifying biological filter in marine & brackish aquaria of all types and is particularly useful for new startups, resulting in cycling in about 7 days  in most cases, if directions are followed, and no competeing bacteria or nothing toxic is added (please read this whole webpage.)  It quickly removes toxic ammonia and nitrite naturally through non pathogenic nitrifying bacterial action.  Even though this product is extremely potent, it may be overdosed at up to 5 times the rated dosage during aquarium emergencies.  It should be your first choice to remove ammonia during emergencies where the filter has been inadvertently killed or when experiencing overcrowding.


Technical Background

MicrōBacter Start XLM 15X is a highly concentrated, selective complex of live, extremely effective microbes and enzymes that rapidly reduces the concentrations of organic nitrogen - i.e. ammonia, and nitrite in marine and brackish ecosystems, leading to greatly improved water quality and much faster cycling. Use of MicrōBacter Start XLM does not alleviate the requirement for regular partial water changes to help maintain proper concentrations of elements that are vital to long-term health and survival of aquarium inhabitants.

Notes - It is normal that clumps may form in the product and the product and the aquarium may have an “earthy” smell or smell “off” and the aquarium water could become cloudy and the smell and cloudiness could remain for many hours after using. This is due to the bacteria themselves and is an indication of quality and is the reason it is necessary to shake product well immediately before using.


Pitfalls:  There are several reasons why hobbyists do not achieve a fast 7 day (approximately) cycle with this product.  These are all controllable if careful attention is paid.  Even when these factors are present, the tank will still cycle, it will just take more time.  1) Failure to dechlorinate properly.  Always use Brightwell Erāse-Cl to completely remove chloramines and chlorine from tap water. Chloramine and chlorine are lethal to the bacteria in this product and if not removed, will cause it to fail!  2) The overuse of ammonia or using household ammonia!  Ammonia is toxic to bacteria, even though they consume it, just like it is to fish and invertebrates, so if you overdose the ammonia, it will kill some of the bacteria and it will take longer to cycle!  You will still achieve an excellent and strong cycle, it will just take longer, possibly much longer.  Also, if you purchase household ammonia, it may have toxic additives, dyes, surfactants and cleaning agents that will stunt the multiplication of the bacteria in the product.  Brightwell recommends that you use MicroBacter QuikCyclTM as directed and test so that you don't overdose! 3) In a brand new aquarium, there can sometimes be surfactants, mold release compounds or oily chemicals that coat brand new glass, acrylic, tubing and pumps.  These compounds can negatively affect the cycle.  It is therefore recommended that you clean all new parts with a mild soap and water and then RINSE THEM VERY WELL!  (Do not use antibacterial soap!) This should remove the compounds that can stunt the multiplication of the new bacteria  4) Brightwell recommends that you not use any other type of bacteria product until your cycle with this product is complete !!! Do not even use MicrōBacter7 or MicrōBacterCLEAN until the cycle is complete (then you will want to use one of them to help through the "ugly stage".  (MicrōBacterCLEAN   will work best for this.)  5) Do not use live sand and particularly DO NOT USE dry seeded artificial live rock until cycling is complete. There are no dry bacteria species that will be compatible with this nitrifying bacteria product or that are useful to cycle an aquarium at all! To use a dry bacteria will only lengthen the time it takes to cycle by many weeks and increase your work many times!  Wet cycled live rock or even previously cycled wet man made rock will work fine (although this may be a bad idea due to the possibility of introducing parasites or pathogens from another aquarium).  Dry sand is fine to use, but not bagged, so called "live sand"  because the manufacturer will usually introduce other bacteria species to replace the natural bacteria that will die during storage and these will be counterproductive to your cycle.  Also, several so called "probiotic" salts are available.  Again, there are no species of bacteria that are conducive to cycling that are available in a dry form.  Therefore, do not use any salt that is labelled as probiotic or says it contains dry bacteria.  Note:  What to do if you must use live sand or dry seeded live rock - go ahead and use them with the MicrōBacter Start XLM, just realize the cycle will be impeded.  It will take more XLM to seed the system (double the dose if you can) and the cycle will likely take 2 to 4 weeks longer to complete because you are working against the XLM, but when completed, will work just fine.  6) DO NOT USE CARBON IN YOUR FILTER until the aquarium has cycled fully or 30 more days has passed.  DO NOT USE PHOSPHATE REMOVERS, FILTER RESINS, GFO or other non-biological filtration media until the aquarium is over 30 days old or then you register phosphates on your test kit over .04 PPM.  If you do, you will lengthen the cycle.  Bacteria require some phosphate to multiply rapidly!  Use XportTM, MicroBacter LatticeTM or other filtration media that needs to be populated with bacteria!  These will work well.  7)  The addition or dosing too soon of active iodine compounds (such as Lugol's), nitrate removers (such as nopox which is made from poisonous methanol), or other additives that are bacteriacidal.  If you are going to add these, It is a good idea to wait 30 days.

Storage & Shelf Life: Shelf life is typically 18 months from manufacture date (more than twice as long as any other nitrifying bacteria and 8 or more times as long as most others).  Although product can withstand elevated temperatures for short periods of time (a few days), for best longevity and highest potency, keep below 80°F and if possible, it will be best kept refrigerated at 50°F to much prolong shelf life. Do not freeze! Freezing can kill the bacteria.  (This product will usually withstand a freeze or two in transit in the winter, but do not freeze, thaw, freeze thaw and keep from freezing if at all possible.)  If the product arrives frozen, then thaw at room temperature, NEVER MICROWAVE!


A word about substrates: Most aquarium bacteria and certainly those in MicrōBacter Start XLM live on substrates, that is, they attach themselves to surfaces of rocks, piping and any other surfaces that are available.  Most modern aquariums do not have enough surface area.  The advent of artificial "live rock" has made available products made from concrete or plastic that look like live rock, but do not have the porosity, so their surface area is too small to support the number of bacteria needed to properly filter the aquarium.  Brightwell recommends that you provide plenty of bacterial surface area, either through plenty of porous natural aragonite live rock, or by providing additional filtration media, such as our XportTM media which has the highest surface area per unit volume of any medium in the world, or our less expensive MicroBacter LatticeTM.  A good way to judge the porosity of a filtration medium is by weight.  If it is heavy, it is not very porous.  If it is light in weight, like XportTM media, it is full of air and therefore very porous.


Before you get started, you will need:

  1. An appropriately sized bottle of MicrōBacter Start XLM.  At a minimum, you will need 1.2 ml of product for every gallon of aquarium capacity.  For example, if you have a 100 gallon tank, you will need a minimum of 120 ml of MicrōBacter Start XLM.
  2. a good grade of the following test kits:  ammonia, nitrite, nitrate, pH
  3. a bottle of Brightwell Erāse-Cl to remove all chlorine or chloramines (if you skip this, you can kill the bacteria in MicrōBacter Start XLM.)
  4. Of course, you will need an excellent aquarium salt mix, such as Brightwell NēoMarine and purified tap water.  Brightwell recommends the tap water be filtered by Reverse Osmosis with post deionization and that you change your carbon filter regularly.

Instructions & Guidelines

Important: First, use Brightwell Erāse-Cl to completely remove chloramines and chlorine from tap water. Chloramine and chlorine are lethal to the bacteria in this product and if not removed, will cause it to fail! Shake product vigorously immediately before using.  Add the appropriate volume of MicrōBacter Start XLM (see below) to the aquarium in an area of high flow to promote dispersion. Do not use “live sand” or “dry seeded artificial live rock” until cycling with this product is complete for several weeks! (In fact, Brightwell recommends that you do not use dry seeded artificial "live rock" ever.  The best choices are aquacultured live rock, rock from the ocean, naturally cycled artificial rock sold wet, unseeded dry artificial rock, dry florida aragonite, other natural aragonite, marco rock and the like.  Any rock that already contains a bacteria and is dry, will damage the cycling process and in our experience takes too long to cycle and cycles the wrong nutrients - dry seeded rock will not properly cycle ammonia because it is the wrong species of bacteria)

To seed Biological Filtration in new aquaria: Add 30 ml (6 capfuls) of MicrōBacter Start XLM per 25 US-gallons (95 L) of aquarium water. Add one or more hardy fish. Remove filter socks, turn UV-sterilization and/or ozonation and/or protein skimmer off for the complete period of cycling until you are finished dosing this product. Test ammonia and nitrite levels daily or as needed, if either are above .2 ppm, then you can dose MicrōBacter Start XLM again at a lower dose of 10 ml per 25 US-gallons, if desired. At 7 days or longer, Tank is cycled if, and only if, both ammonia and nitrite levels are zero and nitrate is well above zero. If either ammonia or nitrite levels are above zero, then the tank is not yet fully cycled and you should not add fish.  if the nitrate is not above zero (at least .25 ppm), then tank is not yet fully cycled and you should not add fish.

To replace bacteria killed by extensive cleaning of substrates and surfaces: Add 10 to 30 ml per 25 US-gallons (95 L) depending on perceived damage to filter bed, and ammonia level.

To replace bacteria killed by medications, overcrowding or emergencies: First, dose the aquarium with Brightwell Erase Cl to detoxify the ammonia until the bacteria can consume it!  Dose daily with Erase Cl, if necessary to keep ammonia under control until the bacteria are fully in control.  Add 30 ml per 25 US-gallons (95 L) or more of MicroBacter Start XLM, depending on perceived damage to filter bed. Then add 5 ml per half hour until ammonia levels come down.

To perform a Fishless Cycle: Purchase a bottle of MicroBacter QuikCyclTM to use simultaneously with this product, MicrōBacter Start XLM according to the QuikCyclTM label. Fishless cycling requires both products to be used together. This product will provide the bacteria and the QuikCycl will provide the nutrients.  GO SLOW WITH QuikCyclTM!  All of the ammonia you put in will become nitrate that you will have to remove later.

Ongoing care after the aquarium is cycled: To provide ongoing biological stability to a cycled aquarium: Switch to MicrōBacterCLEAN after tank is fully cycled and one week has elapsed. This will greatly reduce problems during the "ugly stage."  At that point, you can add Reef BioFuelTM to provide a carbon source for the MicroBacterClean, if desired.  If you want to switch to MicrōBacter7 the best time will be when the aquarium has been running for 4 to 6 months. 



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