Fish Tank Water Change Kit: Gravel Vacuums, Conditioners and a 5-Step Routine

Nobody sets up an aquarium because they love water changes. But a partial water change with a gravel vacuum is the routine that keeps the tank looking good between filter cleanings. One fishkeeper called their siphon “The unglamorous tool that keeps a 20-gallon from turning into soup,” and that is about right.

This guide puts together a simple water change kit for a freshwater fish tank: a gravel vacuum (siphon) to pull out dirty water and debris, and a water conditioner to make tap water safe for the refill. It includes a tank-size table and a five-step routine you can follow the first time.

Short version: Get a siphon that suits your tank’s depth, a bucket used only for the aquarium, and a tap water conditioner. Siphon out part of the water while cleaning the gravel, refill with conditioned water close to the tank’s temperature, and test your water so you know how often your tank needs it.

What Goes in a Water Change Kit

• A gravel vacuum (siphon). A wide tube that goes into the gravel, a hose, and a way to start the flow (a squeeze bulb or a press pump), so you never have to start it by mouth.
• A bucket used only for the aquarium. Never one that has held soap or cleaners.
• A water conditioner (dechlorinator). Tap water usually contains chlorine or chloramine, which the conditioner makers say must be removed before the water goes in the tank.
• A test kit. Not strictly part of the change, but it tells you how often your tank needs one. See our aquarium water test kits guide.
• An old towel. For the drips.

Tank Size Guide

How much and how often to change depends on how many fish you keep, your test results and your tap water; one percentage does not fit every tank. The table uses a 25% change as an example, with the Seachem Prime dose worked out from its label (2 drops per gallon for small volumes, or 5 mL per 50 gallons). Always dose for the volume of new water you are adding and follow the label on the product you use.

The Picks, Up Close

Tetra Water Cleaner Gravel Siphon for Aquariums up to 55 Gallons

Tetra Water Cleaner Siphon — Check price on Amazon

Tetra’s siphon is the simple starting point and the one we also suggest in our tank setup guide. Tetra rates it for aquariums up to 55 gallons and includes the gravel siphon, a priming bulb to start the flow, and a clip that holds the hose on the bucket. That clip matters; as one reviewer put it, “Unless you have two people cleaning a tank … you likely will have the tube bend at the wrong time and spill water.” Move the tube through the gravel to lift out debris as the water drains.

Best for: Most tanks from 10 to 55 gallons, and first-time fishkeepers.

Laifoo 5ft Aquarium Siphon Vacuum Cleaner for Gravel and Sand

Laifoo 5 ft Siphon — Check price on Amazon

The Laifoo is a basic squeeze-ball siphon with a 5-foot clear hose that the maker says is anti-kinking and has no odor. The gravel tube sinks and has a removable filter screen inside to stop gravel and small fish from being pulled up the hose. Pinch the ball a few times and the water starts flowing on its own. It is a good low-cost choice for small and medium tanks; check the tube length against your tank’s depth before buying.

Best for: Small and medium tanks, sand or gravel, on a budget.

QZQ Aquarium Gravel Cleaner Vacuum Kit

QZQ Gravel Cleaner Kit — Check price on Amazon

The QZQ kit is a manual press-pump siphon with extras. You press the pump a few times to start the flow, with no electricity needed, and the vacuum pipe has a filter net to block gravel. The kit includes two water pipes and a joint, a flow clip, a hose clip, an outlet hose, a fishing net, an algae scraper and an aquarium thermometer sticker. It suits new keepers who want the small tools in one box.

Best for: New tanks that need a starter set of cleaning tools.

Seachem Prime, 500 ml

Seachem Prime — Check price on Amazon

Prime is a concentrated conditioner for freshwater and saltwater tanks. Seachem says it removes chlorine and chloramine and detoxifies ammonia, nitrite and nitrate for 48 hours. The label dose is one 5 mL capful per 50 US gallons of new water, or 2 drops per gallon for small volumes. Because so little goes so far, it takes a moment to get used to; as one buyer wrote, “I was honestly confused by the dosing at first because such a tiny amount treats so much water.” Prime does not replace testing; see our ammonia spike guide if your readings climb.

Best for: Most tanks, especially newer ones, and keepers who want one bottle to last a long time.

API Tap Water Conditioner, 16 oz

API Tap Water Conditioner — Check price on Amazon

API’s conditioner is the simple, widely available option. API says it neutralizes chlorine, chloramines and other chemicals in tap water, and is meant for use when adding or changing water and when adding new fish, in freshwater and saltwater aquariums. It is a super-strength, concentrated formula, so measure carefully and follow the dose on the bottle.

Best for: Established tanks where you just need tap water made safe.

How to Do a Water Change in 5 Steps

1. Get ready. Unplug the heater and any equipment that could run dry when the water level drops (check your equipment’s instructions). Wash your hands with plain water, no soap, and set the bucket on a towel below the tank.
2. Start the siphon and clean the gravel. Put the tube in the tank, start the flow with the bulb or pump, and clip the hose to the bucket. Push the tube into the gravel in one section at a time, let the debris lift, and pinch the hose to slow the flow. Keep an eye on small fish near the tube.
3. Stop at your planned amount. Lift the tube out of the water when you reach the amount you planned, such as the example in the table above. Clean a different section of gravel next time rather than all of it at once.
4. Prepare the new water. Fill the clean bucket with tap water close to the tank’s temperature. Add conditioner for the amount of new water, following the label, and stir.
5. Refill slowly and restart. Pour gently onto a decoration or your hand so the gravel isn’t stirred up, refill to the normal level, then plug the heater and equipment back in and check they are running. Test your water later in the day or the next day.

Some cloudiness right after a gravel clean is common; our guide to why a fish tank goes cloudy after cleaning explains what is normal and what isn’t.

FAQ

How often should I change my fish tank water?

It depends on how many fish you keep, how much you feed, your filter and your test results. Tetra describes a 30% change every 30 days for its siphon; some keepers change smaller amounts more often. Let your test kit guide you.

Do I need a water conditioner if I let tap water sit out?

Letting water sit does not remove chloramine, which many water suppliers use. A conditioner made for aquariums is the simple, reliable way to make tap water safe for fish.

Should I take the fish out during a water change?

No. Leave them in the tank. Removing fish adds stress and risk. Just work slowly around them.

Can I use these siphons in a turtle tank?

Yes, a siphon works the same way, but turtle tanks get much messier. See our turtle tank cleaning tools guide for picks made for that job.

Final Take

A good water change kit is cheap and simple: a siphon, a bucket and a conditioner. The Tetra Water Cleaner is the easy siphon for most tanks up to 55 gallons, the Laifoo is the low-cost squeeze-ball option, and the QZQ kit bundles a press-pump siphon with a few starter tools. For the refill, Seachem Prime is the concentrated conditioner that lasts a long time, and API Tap Water Conditioner is the simple budget bottle. Use the table as a starting point, test your water, and adjust to what your tank needs.