DIY Magnetic Glass Cleaner Budget Guide: Neodymium and Pad
A branded magnetic glass cleaner like the Magfit Mag-Float retails at SGD 25-50 in Singapore depending on glass thickness, yet the inner workings amount to two opposing neodymium magnets, a felt pad and a scratch-free abrasive. DIY magnetic cleaner aquarium builds replicate the same internals for under SGD 8 in parts and offer the customisation advantage of matching exactly to your tank’s glass thickness, which the off-the-shelf models often get slightly wrong. This guide from Gensou Aquascaping at 5 Everton Park covers the magnet sizing, the housing build, and the critical encasement that keeps the magnets dry across years of use.
Materials and Tools
Two N52 neodymium magnet blocks sized 25x10x4mm or 30x15x5mm depending on glass thickness — Shopee suppliers sell pairs for SGD 4-7. A blackboard eraser felt pad (SGD 1.50 at Daiso) for the inside face. A small piece of fine-grit scratch pad or melamine foam (SGD 1) for the outside abrasive face. Two-part epoxy resin or marine epoxy (Selleys 5-Minute, SGD 5 at any HDB hardware shop). A small plastic container or 3D-printed housing for the inner block. Total under SGD 10.
Why This DIY Saves Money
Mag-Float Small retails at SGD 25, Medium at SGD 38, and Large at SGD 50-65 in Singapore aquarium shops. The DIY equivalent at SGD 8 saves SGD 17-57 depending on tank size. For multi-tank fish rooms running three or four cleaners, the savings compound to over SGD 150. The magnet strength on N52-grade neodymium often exceeds the off-the-shelf product’s performance because retail brands cut costs with weaker N42 magnets.
Step 1: Size the Magnets to Glass Thickness
Glass thickness drives the magnet pull strength required. For a 6mm pane, two N52 magnets at 25x10x4mm work well. For 10mm pane, scale up to 30x15x5mm. For 12mm or thicker, double up the magnet stack to 8mm thickness on each side. Measure your glass with a digital caliper or check the tank manufacturer specs. Undersizing the magnets means the cleaner won’t drag across the algae effectively.
Step 2: Build the Inside Housing
Find a small plastic container slightly larger than the magnet — a Daiso bead storage box or a 3D-printed housing works. Glue the magnet inside the box with a few drops of epoxy and let cure for thirty minutes. Cut the felt eraser pad to fit the outer face of the housing — this is the inside-tank cleaning surface. Glue the felt to the housing with epoxy.
Step 3: Build the Outside Housing
Repeat the housing build with the second magnet for the outside-glass piece. Make this housing slightly larger than the inside piece so your fingers can grip it comfortably. Glue the scratch-free abrasive pad — fine green scrubber or melamine foam — to the inside face. The abrasive grade matters; melamine foam is gentle enough for acrylic but glass tanks tolerate green scrubber pads.
Step 4: Test the Magnetic Pull
Hold the inside housing against a 10mm sheet of glass and bring the outside housing close on the other side. The magnets should snap together with significant force. If the pull feels weak, the magnets are too small or you have a stack of two glass panes (e.g. on a tank with bracing). Add a second magnet pair to either housing for thicker glass.
Step 5: Seal With Epoxy
Mix two-part marine epoxy and brush a complete coat across both housings, sealing every seam. Pay particular attention to the magnet-housing interface — water ingress here corrodes the neodymium within weeks and the magnet swells, splits and loses pull. Two coats of epoxy is the minimum. Allow seven days cure before water contact.
Step 6: Float Test the Inside Piece
A common feature of branded magnet cleaners is buoyancy — when the inside piece detaches from the outside piece, it floats to the surface rather than dropping into the substrate where it gets buried. Add a small piece of foam to the inside housing to give it positive buoyancy. Test in a bucket of water — it should rise slowly, not bob aggressively.
Sealing and Curing
The two-part marine epoxy must cure for a full seven days before tank introduction. Singapore humidity actually accelerates epoxy cure compared to drier climates, but the chemistry still demands the full week. Test the cured surface with a thumbnail — fully cured epoxy resists fingernail dent. Tacky surfaces mean incomplete cure and require another forty-eight hours.
Aquasafe Test Before Use
Submerge the cured inside piece in a glass of dechlorinated water with two ghost shrimp for forty-eight hours. Healthy shrimp confirms the epoxy and plastics are aquasafe. Smell the unit at the end of the soak — any solvent or plastic odour signals incomplete cure. White vinegar test on the epoxy surface — full cure shows no bubbling or discolouration. Browse complementary tools across the aquascaping tools range.
Maintenance, Lifespan and Pitfalls
A properly built magnetic cleaner lasts five to ten years if the epoxy seal stays intact. The felt and scrubber pads wear out and need replacing every six to twelve months — pull off with a sharp knife and re-glue fresh pads. Re-coat the housings with epoxy every two years as preventive maintenance. Pair with glass-friendly algae control supplements from the water care range.
Common pitfalls — skipping the buoyancy float means the inside piece sinks to the substrate when separated, picking up gravel grit on the felt that scratches the glass on next use. Cheap N42 magnets lose pull above 60°C, and the heat from a Singapore afternoon sun on a south-facing tank degrades them faster than expected. Never use the same DIY cleaner across multiple tanks because cross-contamination of pathogens travels on the felt.
Related Reading
emilynakatani
Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
