Point Four™ Microbubble Oxygen Diffuser – Ultra Fine Bubble Technology for Efficient Gas Absorption

The Point Four™ Microbubble Oxygen Diffuser (MBD) is a ceramic plate diffuser built for dissolving pure oxygen or carbon dioxide in aquaculture systems. Its ultra-fine pore ceramic plate produces a dense cloud of bubbles roughly 100–500 microns across, and the flat plate design keeps bubbling uniform over the whole surface while minimising bubble coalescence — achieving gas absorption rates in excess of 80%, depending on depth and flow rate. When you’re paying for bottled or generated oxygen, that efficiency shows up directly in your running costs. Point Four diffusers have been in commercial aquaculture use since 1988.

Which MBD size do I need?

Pick the diffuser by the gas flow each tank needs — the range runs from the compact PMBD75 at up to 0.75 LPM through to the 1.3 m MBD1200 at up to 12 LPM. The design is modular: several diffusers can run from one regulated supply through a distribution manifold with a flowmeter on each line, and you can add or remove diffusers as biomass and stocking density change. Sizing depends on your species, biomass, water temperature and tank depth — talk to us if you’d like help matching diffusers to your system.

Specifications

Model	Overall size (mm)	Weight	Recommended flow	Max flow @ 3.5 bar	Gas connection
PMBD75	220 × 70	0.45 kg	up to 0.75 LPM	2.2 LPM	6 mm (1/4″) hose barb
MBD100	370 × 45	0.54 kg	up to 1.5 LPM	4.5 LPM	6 mm (1/4″) hose barb
MBD300	390 × 83	1.3 kg	up to 3 LPM	9 LPM	1/4″ NPT female
MBD600	700 × 83	2.3 kg	up to 6 LPM	18 LPM	1/4″ NPT female
MBD900	1020 × 83	3.3 kg	up to 9 LPM	27 LPM	1/4″ NPT female
MBD1200	1320 × 83	4.3 kg	up to 12 LPM	36 LPM	1/4″ NPT female

Bubble size is approximately 100–500 microns across all models. Construction is an ultra-fine pore ceramic plate set in a rigid aluminium base with solid brass fittings (MBD series); the PMBD75 uses a weighted plastic base.

What pressure and plumbing does it need?

Run each diffuser at a bubbling pressure of 25–35 psi (1.7–2.4 bar) from a regulated supply. A typical multi-tank setup is an oxygen regulator feeding a distribution manifold, with an individual flowmeter to each diffuser and a pressure relief valve protecting the line. Use oxygen-rated line between the manifold and diffusers — see our hose and tubing range.

What applications are they suited to?

MBD diffusers are used wherever high-efficiency dissolution of a purchased gas matters: pure oxygen supplementation in RAS, hatchery and broodstock tanks, holding and growout tanks, high-density live fish transport, emergency and backup oxygen systems, and CO₂ dosing.

Maintenance

The ceramic plate is the working part of the diffuser — periodic cleaning keeps bubbling performance consistent, and the plate-in-base construction is straightforward to service. Contact us for advice on cleaning or replacement plates.

Browse the rest of our airstones and diffusers, or see our oxygen and ozone equipment for regulators, monitoring and supply gear to pair with your diffusers.