Brightwell MicroBacter7 — complete bioculture for reef cycling and nutrient control

The Brightwell MicroBacter7 is a complete bacterial culture built to seed the biological filtration of a new marine or reef aquarium and to keep water clear and lean on a running system. Formulated in the United States by Brightwell Aquatics, the mix combines non-pathogenic aerobic and anaerobic microbes with natural enzymes — a blend Brightwell has been selling for more than 12 years.

A visible change in water clarity typically shows up within 30 minutes of dosing. Over the longer term the culture works on organic nitrogen, ammonia, nitrite, nitrate, phosphate, and organic carbon — useful both during a fishless cycle and as a weekly maintenance dose on a mature SPS reef.

What MicroBacter7 is for and when to use it

Cycling a new aquarium — seed the filter bed and rockwork to establish nitrifying and heterotrophic bacteria.
Maintaining a stable tank — reinforce the bacterial population weekly after a water change or a new livestock addition.
Lowering NO₃ and PO₄ — complement an existing probiotic method or replace a bacterial population lost after treatment.
Recovery after an incident — partial loss of bacteria following a medication treatment, an ammonia spike, or an aggressive sump clean-up.

Brightwell official dosing

Stable, low-nutrient systems: 5 mL (1 capful) per 50 US gal (189 L) weekly; alternatively 1 mL per 50 US gal daily, or 1 mL per 25 US gal every other day.
Medium to high-nutrient systems, or cycling: 5 mL (1 capful) per 25 US gal (95 L).
Turn protein skimming and UV sterilization off for 4 hours after dosing.
Do not exceed 1 mL per 25 US gal per day.

Brightwell notes that MicroBacter7 is not intended to be used at the same time as MicroBacter QuikCycl.

Specifications

Brand: Brightwell Aquatics (made in the USA)
Available sizes: 125 mL, 250 mL, 500 mL, 1 L, 2 L, 4 L, 20 L
Composition: proprietary blend of non-pathogenic microorganisms and natural enzymes in purified water
Targets: organic nitrogen, ammonia, nitrite, nitrate, phosphate, organic carbon
Compatibility: marine and reef aquariums, plus freshwater systems
Storage: away from light, cool; refrigeration not required per Brightwell; manufacturer states a 2-year shelf life in the dormant state

Why choose Brightwell at ReefSolution

Brightwell MicroBacter Start XLM — the concentrated bacterial culture paired with QuikCycl for a full fishless cycle.
Brightwell MicroBacter QuikCycl — the ammonia source that drives a fishless cycle (not to be mixed with MicroBacter7).
Brightwell MicroBacter Clean — the detritus and biofilm-oriented version when organic load exceeds what MB7 covers.

Frequently asked questions

Can MicroBacter7 be dosed with a dosing pump?

Yes — Brightwell publishes a daily dose (1 mL per 50 US gal in a stable system, or 5 mL per 25 US gal during a cycle) that fits an automated schedule. Brightwell's published constraint is to turn the protein skimmer and UV sterilization off for 4 hours after each dose, so a dosing pump has to be programmed inside that window, ideally synchronized with a skimmer/UV pause via an aquarium controller or a timer.

Does MicroBacter7 need refrigeration?

No — Brightwell states that the culture is supplied in "suspended animation" and that refrigeration is not required. Storing the bottle closed, cool, and away from light is enough. The manufacturer-published shelf life is 2 years in that state.

Can MicroBacter7 be combined with MicroBacter QuikCycl?

No — Brightwell states that MicroBacter7 is not intended to be used simultaneously with QuikCycl. For a full fishless cycle, Brightwell recommends pairing MicroBacter Start XLM (bacteria) with MicroBacter QuikCycl (ammonia source); MicroBacter7 is the long-term maintenance and reinforcement product.

How long should the skimmer stay off after dosing?

Four hours per Brightwell's official product sheet. The same window applies to UV sterilization. After that, skimmer and UV can resume normal operation — the microbes have had time to disperse and colonize the substrate, rockwork, and sump.