Match the tool to the tank material
The one decision that matters most happens before the scraper touches the water. Glass tanks tolerate a lot: a handled algae pad, a magnetic cleaner, even a blade scraper for stubborn green spot algae. Acrylic tanks tolerate almost none of it — a blade, a gritty pad or the wrong side of a magnetic cleaner will cut fine scratches that cloud the pane forever and give future algae a foothold. If your tank is acrylic, use only pads sold as acrylic-safe, keep them spotless, and accept slower work as the price of a clear pane. For glass, reserve the blade for the hard, flat green spots that pads smear around, and hold it flat and shallow so its corner never digs in.
The grain of sand that ruins a pane
Most scratched aquariums were not damaged by the wrong tool but by the right tool carrying a stowaway. Sand and fine gravel lodge in scraper pads and under magnetic cleaners, and one downward stroke then ploughs a white line through the viewing pane. Rinse the pad before you start, run a finger across its face to feel for grit, and after the first stroke or two, check again. Keep the scraper a finger's width above the substrate at the bottom of each pass and lift away rather than dragging back up through the sand line.
Work top to bottom, then change the water
Start at the waterline, where the film is thickest, and work down in slow, overlapping strokes. Loose algae drifts into the water column as you go, which is why the glass clean belongs immediately before a partial water change: the siphon takes out the floating debris instead of letting it settle on plants and gravel to decompose. A magnetic cleaner lets you tidy the front pane between full cleans without getting your hands wet — park it in a back corner out of sight, and move it slowly so the inner half never bounces across the surface collecting grit.
Reading the algae you are scraping
The growth itself tells you about the tank. Soft brown film on a new setup is usually diatoms and fades as the aquarium matures. Green dust that wipes off easily points to generous light. Hard green spots that need a blade mean the light is strong or long and nutrients are plentiful — scrape them, then shorten the lighting period slightly and look at feeding amounts, or you will be scraping the same spots every few days. Algae only on the front pane is cosmetic; a heavy coat on every surface is the tank asking for a maintenance adjustment, not just a cleaner pane.
Finish outside, gently
For the outside of the glass, use a soft cloth dampened with plain water or a cleaner made for aquarium exteriors, sprayed onto the cloth rather than the tank so nothing drifts into the water. Household glass sprays used carelessly near an open top are a real poisoning risk, and they leave the outside smeared besides. Keeping the front pane on a rhythm — a quick pass each week, deeper attention monthly — stops the job ever becoming a battle, and KinsLe Care Teams can fold glass cleaning into the household's water-change duties so it happens on schedule, marked done by whoever picked up the scraper.