ReefMat 500 Retainer Grid

Replacement Mat Retainer Base for Red Sea ReefMat 500 (part R35455)

This is a printable replacement for the black hex-grid base plate that clips under the ReefMat 500 mat retainer. It holds the fleece against the lower rollers. I modeled it from measurements of my own unit after the original went missing. It’s designed for PETG and has been printed and test-fitted.

Features

• Snaps onto the retainer’s four roller nubs with C-shaped clips. Lift it into place, push it forward, and you’ll feel it click.

• 121 hex openings (7 mm across the flats, 2 mm walls) for free drainage across the full width of the fleece.

• Rounded relief channels under both rollers, so the fleece runs without binding.

• Chamfered hex edges, so the fleece slides over the grid instead of catching on it.

• Heavier clips than the original, with gussets and corner chamfers so they hold up in PETG.

• The rear clip is angled to clear the sloped wall of the housing.

Files

• ReefMat500_Base.stl: the full plate.

• ReefMat500_ClipTest_Front.stl and ReefMat500_ClipTest_Rear.stl: small corner sections with one clip each. Print these first (a few minutes each) to check the fit on your unit before committing to the full plate.

Recommended print settings

• Material: PETG. PLA isn’t recommended for long-term saltwater use. ASA also works.

• Orientation: flat, grid side down, as exported.

• Layer height: 0.2 mm

• Perimeters: 4. This fills the hex walls and clips solid.

• Top/bottom layers: 5 / 4

• Infill: 40% gyroid

• Ironing: on, all top surfaces. This gives the fleece a smooth surface to slide on.

• Supports: enforcers only, painted under the four clip lips. Nothing else needs support.

• Temperature/cooling: print toward the hotter end of your PETG’s range and keep the fan at 30–50%, for stronger layer bonding in the clips.

Installation

1. Hold the plate under the retainer, about 10 mm toward the rear of its final position.

2. Lift it until the clip lips sit just above the four nubs.

3. Push it forward until all four clips click over the nubs.

4. To remove it, pull back firmly and lower it.

Notes

• The clips are designed with about 0.2–0.3 mm of clearance. If the test piece is too tight or too loose, scale X/Y by 1–2%, or adjust your printer’s flow and dimensional accuracy before printing the full plate.

• If the fleece still drags, lightly wet-sand the top surface with 400-grit. Don’t use lubricants in a reef system.

• Rinse the printed part well before it goes in the sump.

Dimensions: about 135 × 88 × 19 mm, including clips.

Not affiliated with or endorsed by Red Sea. ReefMat is a trademark of its owner.