Photo: Coughdrop12 · CC BY-SA 4.0
Gear
Aquarium algae scraper and magnetic glass cleaner
By Fishy Dave
A floating magnet for weekly film on glass, a long-handle stainless blade for stubborn green spot on glass only, and a soft pad when the tank is acrylic. Scrape before the water change so the siphon takes the flakes.
Diagnosis and feeding levers live on aquarium algae. This page is the tool. Pick a cleaner for weekly film, a blade for stubborn green spot, and a pad that will not scratch the pane. A nerite snail helps with soft film between scrapes. It does not replace a pad on the front glass.
Glass magnet vs stainless blade vs acrylic pad
On glass, a floating or weighted magnet is the weekly driver. Move the outside half and the inside pad follows. Soft brown diatom film and light green haze come off in a few passes. Match magnet strength to thickness. A magnet sized for half-inch reef glass will fight you on a thin 10-gallon kit.
Green spot algae and hard coralline need a stainless blade on glass. Long-handle scrapers with replaceable razor-style blades cut dots a felt pad polishes forever. Keep the blade flat, stay off silicone beads, and stop at the sand line.
Acrylic scratches from metal. Use a soft pad or a plastic blade on acrylic, never stainless. Many magnet kits include a softer pad for acrylic. Swap to that pad or buy a plastic scraper made for acrylic tanks.
Grit scratches more than the tool
Most mysterious scratches are sand under the pad. Keep the scrubber above the substrate. If the halves separate, retrieve the inner piece at the surface instead of dragging it through gravel. Rinse the pad when it loads up with debris. A clean felt pad on glass is dull; grit turns it into sandpaper.
Scrape, then change water
Wipe or scrape before you start the water change so flakes and sheets get siphoned out. Doing it after the refill leaves green confetti in water you just conditioned. Pair the scrape with the usual 25-30% change on how to do a fish tank water change and an aquarium gravel vacuum for the mulm on the bottom.
The picks below are a medium magnet for common 10-20 glass, a long stainless blade for hard green spot on glass, and an acrylic-safe pad search when the tank is plastic. Two of the three is enough for most homes. We may earn a commission if you buy. See the affiliate disclosure.
What we would buy
Aqueon algae cleaning magnet, Medium
Common size for many 10-20 gallon glass tanks. Outside half drives an inside pad so you wipe film without soaking your arm. Ships with glass and acrylic pad options; use the soft one on acrylic.
Match magnet strength to glass thickness. Too strong on thin nano glass is hard to drag and can pinch silicone corners. Keep the bowed pad above the sand so grit does not ride under it. Skip a second magnet if a small pad already clears your viewing pane.
See this listingMiguCo stainless algae scraper with spare blades, 25.6 inch
Long-handle stainless blade for green spot and hard patches a felt magnet will not lift. Extends to about 25.6 inches, right-angle head for corners, ten spare blades in the box. Glass tanks only.
Never use this on acrylic. Rinse and dry after saltwater so the steel does not pit. Watch the silicone seams and the sand line; a nick on the blade edge can scratch. Skip this if your magnet already knocks green spot down in one pass.
See this listingAcrylic-safe algae pad or plastic blade
When the tank is acrylic, skip metal. A soft scrub pad or plastic scraper blade removes film without the haze a stainless edge leaves. Look for acrylic-safe pads and plastic blades sized for hobby tanks.
Confirm the listing says acrylic or plastic blade before you buy. Rinse grit off every pass. If your Aqueon magnet already includes the soft acrylic pad and that pad still cleans well, you do not need a third tool.
See this listing
Frequently asked questions
Magnet cleaner or blade scraper?+
Use a magnet for soft weekly film on glass so you keep your hands dry. Reach for a long-handle stainless blade when green spot or coralline will not budge on glass. Soft pad or plastic blade only on acrylic. Many people keep one magnet for the weekly pass and a blade for the hard patches.
Will a metal blade scratch acrylic?+
Yes. Stainless and razor blades dig into acrylic and leave permanent haze. On acrylic, use the soft pad that came with your magnet or a plastic blade made for acrylic. Metal is for glass only.
Why did my magnet scratch the glass?+
Usually grit, not the pad itself. Sand and gravel stuck under the scrubber act like sandpaper. Keep the pad above the sand line, rinse it when it picks up debris, and rejoin the halves above the waterline if they separate so you do not scoop substrate.
When should I scrape relative to a water change?+
Scrape first, then siphon. Loosened algae and film float or settle where the gravel vacuum can pull them out. Scraping after you refill leaves flakes in the new water. See how to do a fish tank water change for the 25-30% routine and aquarium gravel vacuum for the tool.