Brightwell MicroBacter Purple-M — purple PNSB bacteria for marine reef systems

The Brightwell MicroBacter Purple-M is a complex culture of non-pathogenic aerobic and anaerobic microbes, including the strain Rhodopseudomonas palustris — a versatile purple non-sulfur bacterium (PNSB). Formulated in the United States by Brightwell Aquatics, it enhances nitrification, denitrification, and organic waste degradation in marine and reef systems while supporting full nutrient remineralization.

The culture is supplied in live suspended state. Rhodopseudomonas palustris shows cream to light brown under oxygen-rich conditions and develops its purple pigment under low-oxygen illuminated conditions. Brightwell keeps the strain in an oxygen-adapted form — more compatible with marine aquarium parameters, less stressful on the bacteria when added, and with extended shelf life.

What MicroBacter Purple-M is for and when to use it

Full biological amplification — nitrification (NH₃, NO₂), denitrification (NO₃), and organic-carbon mineralization handled at once by the same bacterial consortium.
SPS ULNS systems — weekly reinforcement routine for low-nutrient reefs where native biology is fragile.
Recently reset tanks — 2 weeks of high-load dosing to establish the new bacterial population after a loss.
Complement to MicroBacter7 — Purple-M adds the specific purple PNSB strain where MB7 alone does not cover targeted organic-carbon export.

Brightwell official dosing

Low-nutrient systems: 5 mL (1 capful) per 50 US gal (189 L) weekly, or 1 mL per 50 US gal daily.
High-nutrient systems: 1.25 mL (1/4 capful) per US gal weekly for the first 2 weeks.
Shake the bottle well before every dose.
Add into an external biological filtration compartment. Do not inject into a pump intake port.
Turn protein skimming and UV sterilization off for 24 hours after each dose (not 4 hours as with MB7 or Clean — a Purple-M specific).

Specifications

Brand: Brightwell Aquatics (made in the USA)
Available sizes: 125 mL, 250 mL, 500 mL, 1 L, 2 L, 4 L, 20 L
Feature strain: Rhodopseudomonas palustris (purple non-sulfur bacterium, PNSB)
Composition: non-pathogenic aerobic and anaerobic microbes blend
Compatibility: marine and reef aquariums
Storage: refrigeration not required; room-temperature storage with light prolongs activity and maximizes shelf life

Why choose Brightwell at ReefSolution

Brightwell MicroBacter7 — the baseline bioculture to pair with Purple-M for standard nitrification and broad organic degradation.
Brightwell MicroBacter Clean — the detritus-focused complement when tank surfaces still cake up despite the bacterial routine.
Brightwell KoralColor — the biochrome supply for SPS that grow under Purple-M and deserve a parallel coloration boost.

Frequently asked questions

Why 24 hours skimmer off for Purple-M when MicroBacter7 needs only 4?

Brightwell explicitly publishes 24 hours for Purple-M — specific to the PNSB strain Rhodopseudomonas palustris, which needs a long, skim-free window to settle onto substrate and surfaces before skimmer foam exports it. MB7 and Clean use more tolerant strains that recover after 4 hours.

Can Purple-M be dosed on a cycling aquarium?

Yes — Brightwell recommends the "high-nutrient systems" protocol: 1.25 mL (1/4 capful) per US gal weekly for the first 2 weeks. This intensive phase seats the bacterial population in sand, rock, and biological media.

Does MicroBacter Purple-M need refrigeration?

No — Brightwell states refrigeration is not required. Room-temperature storage in a spot with some light (unlike MB7, which is kept in the dark) prolongs PNSB strain activity and maximizes the bottle's shelf life.

Can Purple-M be dosed via a dosing pump intake?

Brightwell recommends against adding directly to a pump intake port. An automated dosing setup can work as long as the injection point is in an external biological filtration compartment (sump, live-rock chamber) — not a return or circulation pump's intake port.