Gear notes

Buying notes for first tanks, test kits, heaters, and sponge filters, not a fake Top 10 with invented scores. If we link out, we may earn a commission. Read the affiliate disclosure.

Warm freshwater aquarium with gravel, plastic plants, ornaments, and a heater. Typical starter-kit look

kit

20-gallon aquarium starter kit

What a first 20-gallon kit should include, and what you will still need to buy.

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testing

Aquarium water test kit

A liquid master test kit for ammonia, nitrite, nitrate, and pH is the instrument that tells you a cycle is real. Strips are a backup, not a replacement.

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$Handheld salinity refractometer with ATC in an open hard case beside a plastic pipette$

testing

Aquarium refractometer for saltwater

Target about 1.023–1.026 specific gravity (roughly 32–35 ppt) for a FOWLR clown or firefish tank. ATC matters. Calibrate with the manufacturer's solution, often 35 ppt fluid, not a drop of RO and hope.

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Freshwater community aquarium that needs conditioned tap water on every partial water change

Gear

Aquarium water conditioner (dechlorinator)

Municipal water usually carries chlorine or chloramine. Buy a bottle that handles chloramine, dose the replacement water, and do not treat a conditioner as a skip-the-siphon card.

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Glass-tube submersible aquarium heater with suction cup and power cord on a dark surface

Gear

What size aquarium heater do I need for my tank?

Plan on about 3 to 5 watts per gallon: 50W for most tropical 10-gallon tanks and 100W for most 20-gallon tanks in a room near 70°F. Buy an adjustable submersible, then read temperature with a separate thermometer.

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Digital thermometer with an external probe sensor and LCD display

Gear

Aquarium thermometer

Heater dials lie. A stick-on strip is the cheap floor. A digital probe or floating glass thermometer is the upgrade. Put it away from the heater tube and believe that number.

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Planted freshwater aquarium under bright overhead lighting with green plants and small fish

Gear

Aquarium LED light for 10- and 20-gallon tanks

Six to eight hours on a timer beats leaving the kit hood on all evening. A full-length LED bar sized to the tank is the usual upgrade for planted 10s and 20s, not a reef-blast fixture and not a ranked light list.

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Aquarium gravel substrate at the bottom of a freshwater tank

Gear

Aquarium gravel vacuum and siphon

Pick a bulb-start siphon for 10–20s, a longer hose or faucet-hookup when buckets suck, and a narrow tube for nanos and sand. This is the tool page; water-change volume lives on the husbandry guide.

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Coarse foam cylinder from an aquarium sponge filter on a plain background

filtration

Sponge filter for small aquariums

A sponge, an air pump, and a check valve. Gentle filtration for bettas, fry, shrimp-safe intakes, and backup bio on a 10–20 gallon, not a ranked HOB shootout.

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Slim hang-on-back aquarium filter mounted on a glass tank rim

filtration

Hang-on-back filter for 10- and 20-gallon tanks

Adjustable HOB filtration for 10s and 20s: reusable foam and ceramic beat disposable cartridges, baffle the outflow for long-fin fish, and expect to reprime after some power cuts.

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External aquarium canister filter standing beside a glass tank with intake and return hoses

filtration

Canister filter for 29- to 75-gallon tanks

External filtration for planted 29–40 communities and fancy goldfish: hose clutter earns its keep, media stacks coarse to bio, prime after opening, and never rinse media in tap water.

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Pile of porous glass ceramic rings used as aquarium biological filter media

filtration

Aquarium filter media

Mechanical foam catches gunk. Ceramic holds the bacteria that finish the nitrogen cycle. Carbon is optional and saturates. Stack coarse to bio to fine, rinse bio media in old tank water only, and stop buying disposable cartridges when foam will do.

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Small sword plant growing from aquarium substrate in a freshwater planted tank

Gear

Aquarium root tabs for planted tanks

Crypts, swords, and Vallisneria want food in the substrate. Push a root tab under the crown, not on top of the gravel. Liquid ferts are a different job for stem plants and epiphytes.

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Small planted freshwater aquascape with a clear sand and gravel substrate bed under low plants and hardscape

Gear

Aquarium sand and gravel for a freshwater tank

Fine inert sand for cories and loaches. Smooth gravel for a community tank you can vacuum. Planted soil only when you want a nutrient bed and will watch early ammonia. About 1 lb per gallon covers a 1 to 2 inch bed in a 20.

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Home freshwater aquarium with plants and fish, the kind of rimmed tank that needs a measured glass or mesh lid

Gear

Aquarium lid for jumpers and evaporation

A fitted lid stops jumpers, cuts evaporation, and keeps cats and curious hands out. Measure the rim opening, leave room for the HOB lip and cords, and pick glass for most freshwater or mesh when a saltwater nano needs more gas exchange.

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Red encrusting algae on aquarium rock in a public tank, the kind of stubborn growth scrapers and magnets pull off viewing glass

Gear

Aquarium algae scraper and magnetic glass cleaner

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.

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Small aquarium air pump with coiled clear airline tubing and a cylinder air stone laid out on a gray surface

Gear

Aquarium air pump for sponge filters

An air pump drives a sponge filter and breaks up the surface so the water holds more oxygen. One small pump runs one sponge in a 5 to 10 gallon, a dual-outlet pump runs two, and a check valve keeps a power cut from siphoning tank water onto the shelf.

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Two green aquarium hand nets on a stone floor, a soft fine-mesh net on the left and a coarser knotted-mesh net on the right

Gear

Aquarium fish net: mesh, size, and handle length

Pick soft, tight mesh, a net head about twice as wide as the fish is long, and a handle that reaches the gravel. Keep one net per tank, and use a cup instead of mesh for corydoras, plecos, and loaches.

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Drum-style automatic aquarium fish feeder mounted above a tank, the kind used for timed flake or pellet portions

Gear

Automatic fish feeder for weekends and short trips

A battery drum feeder drops a set portion while you are gone. Programmable units suit a week away. Simpler timers cover a weekend. Skip them for fry, picky eaters, and long trips with no backup plan.

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A small fish resting on a white PVC pipe fitting used as a hide in a bare quarantine tank

kit

Quarantine tank setup: what a 10-gallon hospital tank needs

A bare 10-gallon tank with a lid, a sponge filter that has lived in your display, an air pump, a 50 watt heater, and its own net and bucket.

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Male albino bristlenose pleco sitting inside a breeding cave on light gravel in a freshwater aquarium

Gear

Aquarium driftwood and caves for a freshwater tank

Malaysian wood and mopani sink after a soak. Spider wood floats for a week or two. Boil small pieces, soak big ones, and expect tea-colored water for a while. A bristlenose cave wants an opening about 1.5 to 2 inches across.

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Red root floaters on the water in a round plant tub, with some held inside a ring of clear tubing

Gear

Floating aquarium plants and a shrimp-safe fertilizer

Red root floaters and Amazon frogbit dim a bright tank and take up nitrogen as they grow. Keep them inside a ring of airline tubing, scoop out about a third each week, and feed them with a copper-free fertilizer if shrimp share the water.

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A group of albino corydoras crowding around a green wafer on pale gravel

Gear

Sinking wafers and pellets for bottom feeders

Bristlenose plecos and otos want veg wafers and blanched zucchini. Corys and kuhli loaches need a protein wafer of their own, dropped after the midwater fish eat or after the lights go off. Start small, then cut back if crumbs are still on the sand later.

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A juvenile clown loach with ich spots hiding inside a resin log ornament, a second loach behind it

Gear

Ich medication and aquarium salt

For white spot in a freshwater tank, buy one ich medication and dose it from the label for your real gallons. Hikari Ich-X and API Liquid Super Ick Cure are the two bottles we reach for. Aquarium salt is an optional extra for hardy fish in a tank without plants, shrimp, or snails.

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Planted freshwater aquarium with neon tetras and guppies under three small clip-on LED lights

Gear

Aquarium light timer

Start a new tank at 6 to 8 hours of light a day and let a timer run it, so the schedule doesn't depend on you remembering. Check whether your light already has a timer built in before you buy one. Then pick a mechanical outlet timer, a digital one, or a smart plug.

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