Answered: 20 Proven Aquarium Cleaning Questions 2026

By David Park · March 9, 2026

Common Aquarium Cleaning Questions

How often should I change the water in my aquarium?

I do a 25% water change every single week for my 55-gallon community tank. If you have a heavily stocked cichlid tank, you might need to change 30-40% twice a week to keep the bioload manageable. Don't wait for the water to look cloudy. By then, nitrates are already spiking. I use the API Master Test Kit to keep nitrates below 20 ppm.

What is the best tool for water changes?

I swear by the Python No Spill Clean and Fill system. It costs around $40-50, but it saves my back from hauling heavy buckets across the living room. You just hook it directly to your sink faucet. It siphons the dirty water out and pumps treated water back in. If you have a smaller 10-gallon setup, a standard $15 siphon and a 5-gallon bucket work perfectly fine.

Should I take my fish out while cleaning?

Never take your fish out during a routine clean. It stresses them out terribly and risks injury from the net. I only remove fish if I am completely tearing down the tank or treating a severe disease in a quarantine setup. Just use a gravel vacuum carefully around them. If you have kids who drop Cheerios in the tank, just siphon them out. Don't panic and net the fish.

How do I clean aquarium glass without scratching it?

For glass tanks, I use a magnetic scraper like the Mag-Float. Make sure you buy the right strength for your specific glass thickness. A Mag-Float Small works for up to 1/4 inch glass, while you need the Large for 1/2 inch panels. If you have an acrylic tank, only use a plastic scraper or a soft microfiber pad. Metal blades will ruin acrylic instantly.

Do I need to wash my filter media in tap water?

Absolutely not. Tap water contains chlorine and chloramine, which will kill the beneficial bacteria living in your sponges and bio-rings. I always swish my filter media in a bucket of old tank water during water changes. Squeeze the sponges until the water runs relatively clear. It doesn't need to be spotless.

How often should I replace my filter cartridges?

Stop throwing away your filter cartridges every single month. That is a marketing gimmick designed to sell you more replacements. I cut the floss off the old cartridge and stuff it into the new one to transfer the bacteria. This isn't the cheapest option, but the Eheim Classic 2213 canister filter uses reusable sponges that last for years. You only need to rinse those coarse sponges every 3-6 months.

What temperature should the replacement water be?

Match the new water to your tank's current temperature within 1-2 degrees. I keep my tropical tanks at exactly 78°F. If your tap water is 65°F, you will shock your fish and trigger ich outbreaks. I run the tap until it feels lukewarm, then double-check it with a digital thermometer before adding it to the tank.

How do I get rid of stubborn black beard algae?

I'll be honest, black beard algae (BBA) is a nightmare to deal with. Spot treating with liquid carbon like Seachem Flourish Excel works well. Turn off your filter, use a syringe to squirt the Excel directly onto the BBA, and wait 10 minutes. The algae will turn red and die off in a few days. Your shrimp and snails will eat the dead stuff.

Is it safe to use soap to clean my tank or decorations?

Never use soap, bleach, or household cleaners inside your aquarium. Even a tiny drop of Dawn dish soap can coat your fish's gills and suffocate them. If you need to sanitize a used tank, I use a 10% bleach solution. Rinse it thoroughly, then soak it in water with 5x the normal dose of Seachem Prime to neutralize the chlorine.

How do I clean the gravel without sucking up my fish?

Use a gravel vacuum with a flow control valve. I hover the siphon just above the substrate if I have tiny neon tetras or cherry shrimp. For larger fish, push the tube deep into the gravel to pull out trapped fish waste. If you have a sand substrate, just hover an inch above the sand to let the waste lift off without burying the tube.

Why is my tank water still cloudy after a water change?

Cloudy water usually means a bacterial bloom or suspended micro-particles. If it is green, you have an algae bloom from too much ambient light. I use a UV sterilizer like the Green Killing Machine for green water issues. For white cloudy water, just wait it out. Your biological filter will balance itself in 5-7 days.

How do I clean hard water stains on the hood?

Hard water stains are just calcium and magnesium buildup. I spray white vinegar directly onto a paper towel and press it against the stain for 10 minutes. The acid breaks down the minerals quickly. Wipe it away with a damp cloth. Don't spray the vinegar directly over the open tank.

How do I clean the outside of the glass?

I use a 50/50 mix of white vinegar and water in a spray bottle. Spray it onto a microfiber cloth, not directly on the tank. This prevents overspray from getting into the water and harming your fish. Wipe the glass down, then buff it dry with a separate clean cloth.

Should I vacuum the gravel in a planted tank?

It depends on your setup. If you use a nutrient-rich soil like Fluval Stratum, I only hover the siphon above the substrate. Digging deep will uproot your delicate stem plants and release trapped ammonia. For tanks with just root tabs and inert gravel, you can vacuum normally.

How do I remove a dead fish safely?

Use a dedicated fish net to remove the body immediately. A decaying fish will cause a massive ammonia spike in a matter of hours. I always check my water parameters with a liquid test kit after finding a dead fish. If ammonia is above 0 ppm, do a 30% water change right away.

Expert Tips for a Flawless Tank

The Toothbrush Trick for Hardscape: Algae loves to grow on driftwood and porous rocks. I keep a dedicated, brand-new toothbrush in my fish room. I scrub the hardscape right in the tank while the filter is running. The filter catches the dislodged algae. It takes about 5 minutes and makes a massive difference.
Pre-mix Your Water for Sensitive Fish: If you keep discus or crystal red shrimp, tap water isn't good enough. I use a 30-gallon brute trash can with a heater and a powerhead. I mix RO water with remineralizing salts to hit exactly 120 TDS. Let it circulate for 24 hours before pumping it into the tank.
Feed Less to Clean Less: Overfeeding is the number one cause of dirty tanks. I feed my fish only what they can consume in 60 seconds. If food hits the substrate, you are feeding too much. Less food means less fish waste and drastically less vacuuming for you.
Keep a Dedicated Fish-Only Bucket: Never use a bucket that has held household cleaning supplies. Even a rinsed bucket can harbor chemical residue. I bought a bright orange $8 Home Depot bucket and wrote 'FISH ONLY' on it with a Sharpie. When your landlord inspects next week, a quick wipe of the outside glass with a 50/50 vinegar mix makes the whole setup pop.

Water Change Tool Comparison

Method	Cost	Best For	Time Required
Python No Spill System	$40 - $60	Tanks over 20 gallons	15 - 20 mins
Standard Siphon & Bucket	$15 - $25	Tanks under 20 gallons	20 - 30 mins
Electric Gravel Vacuum	$30 - $45	Spot cleaning between changes	5 - 10 mins

Frequently Asked Questions

Can I use a regular household bucket for my aquarium?

No, you should never use a bucket that previously held soap or chemicals. Porous plastics absorb residue that can leach into your water and kill your fish. Buy a brand new bucket from a hardware store and label it clearly. Keep it strictly for aquarium maintenance.

How do I clean artificial plants covered in algae?

Take the plastic plants out and soak them in a 5% bleach solution for 15 minutes. The bleach will destroy the algae and turn it white. Rinse the plants thoroughly under hot tap water. Soak them in a bowl of water with a heavy dose of dechlorinator before putting them back.

Do bottom feeders and snails clean the tank for me?

They help eat leftover food, but they still produce their own waste. A pleco or corydora catfish will not vacuum your gravel or erase nitrates. You still need to perform weekly water changes and maintain your filter. Think of them as a cleanup crew, not a replacement for actual maintenance.

What do I do if I accidentally suck up a small fish?

Turn off the siphon immediately and check the bucket or the filter intake. If the fish went into the bucket, gently net it and return it to the tank. If it got pulled into a canister filter, open the canister and carefully retrieve it. Most small fish survive this if you act within a few seconds.