Magnetic Aquarium Glass Cleaners: Glass or Acrylic, Which Should You Choose?
A magnetic glass cleaner, made of two parts separated by the tank wall, lets you scrape off algae without putting your hands in the water or disturbing the fish. A review by Briscoe and Sinha, published in 2002 in the journal Polymer International, on the scratch resistance of polymer surfaces, notes that acrylic (PMMA) scratches noticeably more easily than glass under repeated abrasive friction (study on Google Scholar), a point that directly determines which cleaner model to pick. Find our other comparisons in the accessories section.
Why does the tank's material change everything?
On a glass aquarium, a scraping pad made of abrasive scrub or a hard plastic blade removes stubborn algae effectively without risk. On an acrylic tank, only a soft felt or non-abrasive sponge pad should be used: a single grain of sand caught between the magnet and the wall is enough to leave a visible, permanent scratch on this softer material; our guide to glass or acrylic covers the other differences between the two materials.
How do you choose the right magnet strength?
The thicker the glass, the stronger the magnet needs to be to hold a firm contact between the two halves; a magnet that's too weak slips and leaves streaks without actually lifting the algae. Manufacturers usually list a maximum recommended glass thickness, worth checking before buying for a large tank.
Does a magnetic cleaner cover all your maintenance needs?
No, it only handles the visible glass panels: corners, the substrate and decor still need a scraper blade or a classic algae card as a complement. It fits best into a regular routine, as covered in our weekly maintenance checklist.
How do you avoid accidental scratches?
Before each pass, check that no grain of sand or debris is stuck to the inner pad, rinsing it under clean water if needed. On an acrylic tank in particular, this simple habit prevents most accidental scratches that get wrongly blamed on the material itself rather than on a poorly maintained cleaner.
- Glass: abrasive pad or plastic blade, no particular risk.
- Acrylic: soft felt only, never an abrasive face.
- Strength matched to glass thickness to avoid slipping.
- Check for debris before every pass, especially on acrylic.
Frequently asked questions
Can a glass-rated magnet scratch an acrylic tank?
Yes, almost every time, if the pad is abrasive: always check the model is rated for your tank's material before buying.
Can the magnet hurt the fish?
No, the handled part stays outside the tank at all times; only the inner pad touches the water, with no risk to fish, which naturally move out of the way.
Do you need a different magnet depending on glass thickness?
Yes, an undersized magnet for thick glass loses its grip and becomes ineffective; always check the manufacturer's maximum recommended thickness.
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.