What Aquariums Fit the N-Clear M? Complete Tank, Sump & Adapter Compatibility Guide

Quick answer: The N-Clear M drops into most standard 4-inch filter sock holders without an extra adapter. Larger AIO and rectangular openings may need a model-specific N-Fit M Adapter: M1012 for Innovative Marine 30/40/50 AIO, M1212 as an optional replacement holder for IM SR 60/80/120, M1216 for Waterbox 65.4 or Waterbox 50 Peninsula, and M1218 for most 7 × 4.5 inch rectangular sock openings such as ESHOPPS Mariner.

Trigger Systems note: a Trigger 20 / 20C with a standard round 4-inch sock holder is a direct fit. The Sapphire 20C removable oval-hole plate (approximately 158 × 99 mm) is a different interface and uses M1016; see the N-Fit M adapter table.

First identify the type of opening

A patent-pending cone-style fit instead of a sump rebuild

The N-Clear M uses a patent-pending cone-style fitting system. The interface is designed to settle naturally into many existing 4-inch filter sock holders while the compact lower body occupies the space where the sock already lived. One fitting approach can therefore accommodate small differences among standard holders without asking the owner to rebuild the sump around the filter.

This becomes more valuable on a large system. Some large single-body fleece rollers need a wide dedicated bay, drain-plumbing changes, removal of a sock tray, or changes to baffles and sump layout. M takes a modular approach: keep the existing sock positions, drop a compact M into each active path, and synchronize additional Extensions from one controller. A properly planned multi-M setup can serve systems around 180 gallons without treating one oversized roller as the only way to get enough mechanical-filtration capacity.

Confirmed direct fits: no extra N-Fit M adapter

The systems below use a standard 4-inch filter sock holder or an original 4-inch sock adapter that supports the M directly. The tank name still does not replace a physical clearance check, especially when plumbing hangs over the sock plate.

N-Fit M adapter table

The reviewed Sapphire 39 two-M layout replaces the whole original holder and uses neither the front nor rear removable water blockers on either filter. Do not add a cover for an old third hole after that holder has been removed. Confirm that the original holder is removable, its overall length and width in millimeters, and the clear insertion width between the Eurobraces before applying this arrangement to an unreviewed version.

M adapter examples: check the holder before buying

IM 30/40/50 AIO: use M1012 as the bare adapter, without the two M front water blockers. Waterbox 65.4 AIO or older 50 Peninsula: use M1216. Current Waterbox 50.3 rear-chamber AIO is a different layout and uses Nano with S80120.

Standard 4-inch sock sump: a supported original holder usually needs no extra N-Fit adapter. For a documented two-sock Fiji-30 Advanced Reef Sump 2nd Gen layout, use one Main and one Extension, with one filter in each opening. Still check about 10.6 inches / 27 cm above the sock plate plus service space. Use the measurement guide for modified or unlisted holders.

Clearance checks that still matter

N-Clear M has a 3.55 × 2.9 inch body footprint and is 15.75 inches tall excluding the new fleece roll. The product's chamber guidance and above-plate access serve different purposes:

• Chamber/support check: for nonstandard openings, plan around at least 4.3 × 4.3 × 7 inches of usable chamber space or the exact approved adapter geometry.
• Above-sock-plate clearance: allow about 10.6 inches / 27 cm above the filter-sock plate to the upper, widest roller section, plus a little extra room for installation and removal. Keep pipes, valves, cables, braces, and cabinet obstructions out of this access area.
• Water depth: the body can operate through a broad submersion range, but about the bottom 4–5 inches submerged normally improves flow and noise. A useful starting water depth above the sock plate is roughly 0.4–1 inch.
• Water blockers: most M installs use the appropriate front water blocker to reduce bypass. Exceptions include the bare M1012 setup for IM 30/40/50 AIO and the reviewed whole-holder M1215 replacement layout described above. Follow the instructions for the exact adapter and sump.

How many N-Clear M filters should a multi-sock sump use?

One M is rated for up to 800 GPH. A Main + Extension pair is rated for up to 1,600 GPH, and three filters are rated for up to 2,400 GPH. As a general volume guide, use one M for about 30–60 gallons, two for about 60–120 gallons, and three for about 120–180 gallons. The final number should follow the number of active sock paths, actual flow through those paths, tank volume, and bioload.

For systems in the 120–180 gallon tier with three active 4-inch sock openings, use three M filters as the general configuration guide, subject to actual flow and bioload. This is the core modular advantage: add filtration at the existing sock positions instead of cutting the sump to create one oversized roller bay. If only two openings are filtered, cover the unused path so water does not bypass the fleece. The N-Fit 4-inch Filter Sock Cover is made for that job.

Installation example: Innovative Marine NUVO RFS 50 sump

The confirmed RFS 50 path uses the original standard 4-inch filter-sock openings. N-Clear M fits those openings directly; this is different from the IM 30/40/50 rear-chamber AIO installation that needs M1012. Keep the original sock plate as the supporting surface.

For a standard three-opening RFS section, choose filter count according to active flow paths, flow and bioload. A three-filter arrangement uses one Main, two Extensions and two splitters. Each active path must pass through fleece, or an unused opening must be covered to prevent bypass. Do not apply the UNS first-opening-cover arrangement automatically to an RFS sump: the inlet and usable positions determine the layout.

Check about 10.6 inches / 27 cm of access above the sock plate plus working space for servicing. A standard opening does not remove the need for access around plumbing. CJ's Aquariums installation video in an Innovative Marine sump provides a visual reference for the installation approach; it is not proof that every RFS size or modified sump has identical clearance.

Installation example: UNS R-series three-sock layout

For the confirmed standard three-opening layout, including R90 and the reviewed R150 setup, the inlet overlaps the first sock position. Cover the first opening nearest the incoming water with a 4-inch sock cover, then place one N-Clear M in each of the second and third positions. Those two positions support a Main + Extension setup directly, without extra N-Fit adapters. Keep the original sock plate installed.

Follow the water path: first opening = cover; second and third openings = filters. These are positions relative to incoming water, not fixed left/right directions. For the usual linked layout, put the Extension on the stronger-flow side and the sensor-bearing Main on the farther/slower side. Verify both motors advance during the Manual test.

This arrangement solves the inlet obstruction in that confirmed layout; it does not change the general flow or tank-sizing guidance. An R-series model name alone does not confirm that a modified sump has the same three-opening arrangement. If the original plate has been removed or a different inlet blocks another position, use the measurement guide before choosing a support adapter.

Known non-fit or conditional situations

• Unlisted nonstandard AIO openings: opening width alone does not establish an M fit. Check the reviewed adapter geometry, stable support, usable space below and service access above before ordering.
• Red Sea rear-chamber AIO layouts: current built-in rear chambers are not supported. A Red Sea tank converted to a sump with standard 4-inch socks uses the direct M sump path.
• Missing factory cradle: JBJ and similar direct-fit claims assume the original 4-inch sock cradle remains in place.
• Overhead plumbing: an opening can be correct while a drain, valve, or pipe blocks the motor or prevents roll changes.
• Modified chambers: cutting out a tray or holder changes the support geometry; remeasure rather than relying on the original tank model.

Frequently asked questions

Does N-Clear M fit any 4-inch filter sock?

It fits most standard 4-inch sock holders, but confirm the holder is stable and there is enough space below and above it. Oval openings, overhanging drains, or removed cradles can change the result.

Does N-Clear M fit a Red Sea REEFER sump?

Yes, Red Sea REEFER sump systems are a supported M path. Check overhead pipe and valve clearance. Do not confuse them with Red Sea rear-chamber AIO layouts, which are not currently supported.

Which N-Clear fits Waterbox 50.3 versus Waterbox 50 Peninsula?

Use N-Clear Nano with S80120 for the current Waterbox 50.3 rear-chamber AIO. Use N-Clear M with M1216 for the older Waterbox 50 Peninsula.

Do Innovative Marine SR 60/80/120 tanks need M1212?

Only if the original 4-inch filter sock adapter is missing. With the original holder present, N-Clear M fits without buying M1212.

What if my sump has three sock openings?

Use a filter in each active opening when capacity and layout justify it, or cover unused openings to prevent bypass. The M controller can run synchronized multi-filter setups; see the N-Clear M User Guide for connection diagrams.

What should I send for an unlisted opening?

Send the exact tank and sump model, full chamber measurements, and white-light photos following the adapter measurement request guide. Include both the opening and the space above and below it.