How to Clean a Fish Tank Step by Step: Glass, Gravel and Filter

Regular cleaning is the single most important thing you can do for your aquarium’s health, yet many hobbyists either overdo it or skip crucial steps. This clean fish tank step by step guide from Gensou Aquascaping Singapore — with over 20 years of hands-on experience at 5 Everton Park — walks you through the entire routine, from algae scraping to filter maintenance. Master this process and your fish will thank you with vibrant colour and active behaviour.

Gather Your Tools First

Having everything within arm’s reach prevents dripping water across the room. You will need: an algae scraper or magnetic cleaner, a gravel vacuum (siphon), two clean buckets (dedicated to aquarium use only), a water conditioner, old towels, and optionally a filter brush. Never use soap, detergent, or household cleaning products anywhere near your tank — even trace residues are toxic to fish.

Step 1: Scrape the Glass

Start with the inside glass before disturbing any substrate. A magnetic algae cleaner handles light green film effortlessly — just run it across each panel in slow, overlapping strokes. For stubborn spots or coralline-like deposits, a razor blade scraper works on glass tanks (never on acrylic, which scratches easily). Clean all four sides, including the back panel that many keepers neglect.

Dislodged algae will cloud the water temporarily. That is fine — the water change coming next removes it.

Step 2: Vacuum the Gravel

Push the siphon tube into the substrate in a grid pattern, lifting it once debris flows up and the gravel settles back. Aim to vacuum roughly one-third of the substrate area during each session, rotating zones weekly. This approach removes accumulated waste without destroying the beneficial bacteria living in deeper substrate layers.

For planted tanks with aqua soil, hover the siphon just above the surface rather than plunging in — disturbing nutrient-rich substrate releases ammonia and uproots plants. Bare-bottom tanks are simplest: just glide the siphon across the floor to collect all visible waste.

Step 3: Remove and Replace Water

Siphon 25–30 % of the tank volume into your bucket during the gravel vacuum — you are accomplishing two tasks simultaneously. Refill with fresh tap water treated with a conditioner that neutralises chloramine, which is present in Singapore’s PUB supply. Match the replacement water temperature as closely as possible to the tank — a sudden swing of more than 2 °C stresses fish.

In Singapore’s climate, tap water typically comes out at 27–29 °C, which aligns well with most tropical setups. For cooler tanks (goldfish, hillstream loaches), let the replacement water sit in an air-conditioned room or add a small amount of chilled water to bring the temperature down.

Step 4: Clean the Filter

Filter maintenance should happen every two to four weeks — not every water change. Rinse mechanical media (sponges, filter floss) in the bucket of old tank water you just siphoned out, never under the tap. Chloramine in tap water kills the beneficial bacteria you spent weeks cultivating.

Biological media (ceramic rings, bio-balls) should only be gently swished, not scrubbed. Replace chemical media like activated carbon monthly, or whenever it becomes exhausted. Never clean all filter media at once — stagger replacements to maintain bacterial colonies.

Step 5: Wipe Down the Exterior

Dried water spots and salt creep accumulate on the tank rim, light fixture, and glass covers. A damp cloth with plain water handles most residue. Vinegar on a cloth removes stubborn mineral deposits from the exterior glass — just ensure none drips into the tank. Clean the light cover to maintain full brightness; a dusty cover can reduce light output by 20 % or more.

How Often to Clean

Weekly partial water changes (25–30 %) and glass scraping are the baseline for most tanks. Heavily stocked setups — goldfish tanks, cichlid communities — may need twice-weekly changes. Lightly stocked, heavily planted tanks can sometimes stretch to fortnightly changes, but test nitrates regularly to confirm. If nitrates exceed 20 ppm before your next scheduled change, increase frequency.

Common Mistakes to Avoid

Replacing all the water at once crashes beneficial bacteria and shocks fish. Cleaning the filter on the same day as a large water change doubles the disruption — space these tasks at least a week apart. Using hot water to rinse filter media kills bacteria instantly. Scrubbing decorations with abrasive pads in tap water removes the biofilm that contributes to biological stability.

At Gensou Aquascaping, we follow this exact clean fish tank step by step routine across every client installation in Singapore. Consistency — not intensity — is what keeps tanks looking their best week after week.

Related Reading

• How to Fix Cloudy Aquarium Water Fast: Causes and Solutions
• How to Get Rid of Green Water in Your Aquarium: UV and Blackout
• Best Aquarium Cleaning Kits: Essential Tools in One Set
• Best Aquarium Filter Media and Stacking Order: Mechanical to Biological
• Aquarium Maintenance Cost in Singapore: Monthly Breakdown