Magnetic Glass Cleaners: Choosing the Right Pad or Blade for Your Tank

Every reef and planted tank grows a film of algae or biofilm on the glass within days of a water change. Scraping it off without scratching the pane is one of those small jobs that separates a clear, photo-ready display from one with a permanent haze of hairline marks. Magnetic cleaners solve this by letting you drive a cleaning head on the inside of the glass using a handle on the outside, with no need to get your arm wet past the elbow.

The part that actually touches the glass matters more than the magnet itself. There are three common head types, and each behaves differently depending on what your tank is made of.

Felt pad heads

Felt pads are the softest option and the safest choice for acrylic tanks and acrylic sump baffles, where a plastic or metal blade can gouge the surface permanently. They are gentle enough for daily use on glass too, but felt loads up quickly with coralline algae or hard green spot algae and stops cutting through it. Good for maintenance between deeper cleans, not for stripping established growth.

Plastic blade heads

A plastic blade, like the one fitted to the Mag-Float Large Plus with Blade, cuts through algae film and light coralline far more effectively than felt while remaining safe on standard glass. It will not scratch glass when the blade edge is intact and free of grit, but it is not rated for acrylic, since even a light plastic edge can mark that softer material over time.

Stainless steel blade heads

Stainless blades are for glass tanks only, never acrylic. They are the tool of choice for tanks with heavy coralline buildup or calcified glass that felt and plastic simply slide over. The Flipper Max replacement blades fall into this category and are worth keeping spare, since a stainless edge does the most work per pass but also wears down or nicks the soonest if it meets grit or sand.

Matching magnet strength to glass thickness

The magnet needs enough pull to hold the cleaning head flush against the glass through its full thickness, without being so strong that it is a hassle to slide across the pane or so weak that it slips and drops into the tank. Undersized magnets for thick glass will separate mid-clean, usually right as you are dragging a blade across the front pane, which is the worst possible moment for it to lose grip. Oversized magnets on thinner glass tanks under about 8mm can be hard to manoeuvre and are more likely to trap a stray piece of substrate or shell grit between the pad and the glass, which is actually the main cause of scratches, not the magnet strength itself. Products like the Mag Float Scrape, sized to suit Large and Large Plus units, are built around this pairing so the housing and magnet size are matched from the start rather than mixed and matched.

When to replace a worn blade

• You feel or hear a grinding or catching sensation as the blade passes over clean glass, rather than a smooth glide.
• The blade edge shows visible nicks, chips, or an uneven line when you look at it closely under light.
• You notice fine hairline scratches appearing in a pattern that matches your cleaning strokes.
• The blade has been used on sand or crushed coral substrate that scattered against the glass, since a single grain caught under the edge can groove a line in seconds.

Replacing a blade before it starts marking the glass is far cheaper in outcome than living with permanent scratches in your viewing panel. Keeping a spare blade or pad on hand means you are never tempted to keep using a damaged one out of convenience.

Because felt pads, plastic blades and stainless replacement blades all wear at different rates depending on tank size and algae load, it is worth keeping a couple of spares in the cupboard. Check out our stock list for current magnetic cleaner bodies and replacement heads, since availability shifts as new batches come through. For everything else around tank maintenance and setup, our hardware range and general marine aquariums collection are worth a browse too.