The supplies every aquarium truly needs come down to six categories: a filtration system, a heater, a thermometer, a water test kit, a water conditioner, and a lighting fixture matched to your inhabitants. Everything else is either useful or optional depending on your specific setup. If you are setting up your first tank or doing a gear audit on an existing system, this guide walks through each category, tells you what to buy and what to skip, and gives you specific product names instead of vague generalities.
Whether you keep a 10-gallon freshwater community tank, a 55-gallon cichlid tank, or a nano reef, the core supply list is similar. The differences show up in the details: what kind of filter, what temperature range the heater targets, and what your test kit measures. I will break all of that down below.
Filtration: The Non-Negotiable Starting Point
Every tank needs a filter. The filter performs three functions: mechanical filtration (removing solid particles), biological filtration (housing the bacteria that convert toxic ammonia into less harmful compounds), and chemical filtration (activated carbon to remove dissolved organics and yellowing).
Hang-On-Back Filters
For tanks from 10 to 75 gallons, a hang-on-back (HOB) filter is the most practical choice. The Aquaclear 70 is the most reliable HOB filter I have used across multiple setups. It handles tanks up to 70 gallons, uses replaceable foam, activated carbon, and BioMax ceramic media, and the flow is adjustable. At around $45 to $55, it costs more than the Tetra Whisper series but lasts years longer.
For smaller tanks (5 to 20 gallons), the Aquaclear 30 handles the job at a lower price.
Canister Filters
Canister filters run quietly, hold more media, and are the right choice for tanks 50 gallons and up, especially heavily planted or predator tanks with high bioload. The Fluval 307 handles tanks up to 70 gallons and includes media trays that you can customize. It is quieter than most canisters in its price range, though setup takes more time than a HOB.
The Sunsun HW series offers canister filtration at a much lower price point (around $40 to $60 for the HW-304B). It is not as polished as Fluval but works reliably for the first few years with proper maintenance.
Sponge Filters
For nano tanks or breeding setups, a sponge filter powered by an air pump is the simplest and most affordable option. The Hydro Sponge Filter size 1 or 2 (for tanks 10 to 25 gallons) runs on an air pump like the Tetra Whisper 10 and provides reliable biological filtration. No moving parts to fail, no impeller to clog. Replace or rinse the sponge in old tank water every 3 to 4 weeks.
Heating: Precision Matters More Than Price
Aquarium heaters fail more often than any other piece of equipment, and when they fail, they often stick in the "on" position, cooking your fish. Buying the cheapest heater available is one of the most common and costly beginner mistakes.
Reliable Heater Options
The Eheim Jager is the most consistently reliable fully submersible glass heater on the market. It has a recalibration dial (you can verify and adjust its accuracy against a separate thermometer), a safety shutoff when removed from water, and a 3-year warranty. The 150-watt model handles tanks up to 40 gallons; the 200-watt model covers up to 60 gallons.
For larger tanks or setups where heater failure would be catastrophic (planted tanks with expensive fish, reef systems), consider a titanium heater with an external controller. The Finnex HMO titanium heater paired with a Ranco or Inkbird ITC-306A controller gives you probe-based temperature control that is more accurate than a built-in dial.
General sizing: 5 watts per gallon is the standard starting point. A 55-gallon tank needs a 275-watt heater; most people run two 150-watt heaters so that if one fails, the other keeps the temperature from crashing.
Thermometer: Separate from the Heater
Never rely on the heater's built-in dial to tell you the actual water temperature. Those dials are calibrated imprecisely at the factory and drift over time.
A separate thermometer is a must-have. The JW Pet Fusion Thermometer is a reliable, affordable floating model. Digital thermometers like the Zacro LCD Digital Thermometer give you a display on the outside of the tank with a probe inside, which is convenient for quick checks without opening the tank lid.
Check the thermometer every time you feed your fish. Temperature drift happens slowly and is easy to miss without regular monitoring.
Water Test Kits: Know What Is in Your Water
You cannot manage aquarium water quality without testing it. Test strips are fast and cheap but notoriously inaccurate. Liquid test kits are slower to use but accurate enough to make real decisions.
The API Freshwater Master Test Kit
For freshwater tanks, the API Freshwater Master Test Kit tests ammonia, nitrite, nitrate, and pH. It includes enough reagents for 800 tests total across all four parameters. This is the one kit I recommend without hesitation to every freshwater keeper. It costs around $25 to $30 and covers everything you need to monitor a new tank through the nitrogen cycle and ongoing.
Saltwater Testing
For reef tanks, you need additional parameters: alkalinity, calcium, and magnesium. The Salifert test kits are accurate and widely used. The Red Sea Pro Multi Test Kit covers all three in one package. For a nano reef, test these parameters weekly when the tank is new and monthly once it is established.
A refractometer (not a plastic hydrometer) is also essential for saltwater: the Milwaukee MA887 is a reliable, affordable option that gives accurate salinity readings.
For a full review of filtration and equipment options at different price points, see our best aquarium equipment guide.
Water Conditioner and Dechlorinator
Tap water contains chlorine and chloramine, both of which kill the beneficial bacteria in your filter and stress fish. Adding a dechlorinator before any water change or initial fill is non-negotiable.
Seachem Prime is the most effective and cost-efficient dechlorinator available. A 500 mL bottle treats 5,000 gallons at the standard dose, which comes to a fraction of a cent per gallon. It neutralizes chlorine, chloramine, and temporarily detoxifies ammonia and nitrite at double dose, which is useful during a cycle or ammonia spike. Buy the 500 mL or 1-liter size; the price per dose drops significantly versus the small bottles.
Lighting: Match Your Setup
Light requirements vary more than any other category depending on what you keep.
Freshwater Fish Only
Fish need a day/night cycle, but they are not demanding about light intensity. A basic fluorescent or LED strip light works fine. The Nicrew ClassicLED is a budget-friendly option that works for fish-only and low-light planted tanks. It runs about $20 to $35 depending on length.
Planted Freshwater Tanks
Plants need more light and, for demanding plants, the right spectrum. The Fluval Plant 3.0 LED is a strong choice for medium to high-light planted tanks up to 48 inches long. It has an app-controlled dimmer, programmable sunrise/sunset, and a spectrum tuned for plant growth. At $150 to $200 it is an investment, but it grows demanding plants reliably.
For low-tech planted tanks with low-light species like java fern, anubias, and hornwort, any LED fixture with at least 30 PAR at the substrate is sufficient.
Reef Tanks
Corals need much more light intensity and the right spectrum. SPS corals need 200 to 400 PAR at the coral surface. For a nano reef (under 20 gallons), the AI Prime 16 HD and the Radion XR15 are the dominant choices among serious reefers. For a 50 to 75-gallon mixed reef, the Kessil A360X or a pair of AI Primes work well.
Gravel Vacuum and Water Change Equipment
Water changes are the most effective maintenance activity in any tank. The tools that make them easier are worth having.
A Python No-Spill Clean and Fill is the most convenient water change tool for tanks 20 gallons and larger. It connects to your faucet, siphons water out of the tank directly to the drain, then lets you refill by reversing the flow, all without carrying buckets. At $40 to $60, it pays for itself in time and effort within the first few months.
For smaller tanks or situations where you need more precise gravel vacuuming, a standard Lee's Economy Gravel Vacuum with a rubber squeeze bulb works well.
FAQ
How much should I budget for aquarium supplies to get started? A functional freshwater setup for a 20-gallon tank costs roughly $100 to $150 in supplies: a filter ($25 to $45), heater ($20 to $30), thermometer ($5 to $10), test kit ($25 to $30), dechlorinator ($10 to $15), and a basic light ($20 to $35). The tank itself and decor are separate. Reef tanks cost significantly more, typically $300 to $500 in equipment for a 20-gallon nano, not counting the live rock and livestock.
Do I need a protein skimmer for a freshwater tank? No. Protein skimmers are designed for saltwater aquariums. They skim dissolved organic compounds from seawater using the surface tension difference that saltwater provides. They do not work in freshwater. For freshwater tanks, regular water changes and a good filter are the equivalent tools.
What supplies can I skip when starting out? You can skip UV sterilizers, CO2 systems, automatic top-off units, and media reactors when you are first starting. These are valuable tools for more advanced setups but are not required to keep a healthy tank. Master the basics first: stable temperature, good filtration, regular water changes, and consistent feeding. Add specialized equipment once you have the fundamentals solid.
How often should I replace aquarium filter media? Biological filter media (ceramic rings, bio balls) should never be replaced all at once. Rinse it in old tank water every few months to remove debris, but keep it indefinitely. Mechanical media (filter floss, sponge) should be rinsed weekly and replaced when it falls apart. Activated carbon should be replaced every 3 to 4 weeks in freshwater and every 2 to 4 weeks in saltwater.
Conclusion
The supplies that actually matter for a healthy aquarium are fewer than most beginners expect. A reliable filter, an accurate heater and thermometer, a liquid test kit, Prime dechlorinator, and appropriate lighting cover the fundamentals for any system. Buy quality where it counts (heater, test kit, filtration) and save money where it does not (decor, basic cleaning tools). Once you have the core equipment dialed in, explore the top aquarium equipment guide to find upgrades worth adding as your system matures.