Tank kit

The Marineland Bio-Wheel LED Aquarium Kit 20 came with the second-best filter of the bunch, but its light was dim and the kit cost one and a half times as much as all the other kits at the time of our testing.

We were intrigued by the affordable Elive Aqua Duo 20 kit’s optional aquaponics filter, which allows you to grow a terrestrial plant on top of the filter to help reduce fish waste. But the setup looked a little strange, and as the tank was explicitly designed for this aquaponics setup, it makes little sense without it.

The Tetra 20 Gallon LED Aquarium Kit looked almost identical to the Aqueon kit, except with an inferior filter and five free plastic plants. We value the filter more.

Standalone tank

During our testing, we had difficulty finding any glass tanks available online from reliable retailers due to how hard it is to ship just one empty glass box. When we first published our results, we recommended the Aqueon 20-gallon tank and the Innovative Marine Nuvo Black 20 tank, but neither model is available online anymore.

We also looked at the 18.1-gallon AquaMaxx low-iron rimless aquarium, but it cost slightly more than other tanks we considered, held fewer gallons, and had a less traditional shape. Still, it’s a pristine tank, and it could be a great choice if you want your tank to be viewable from all sides.

If you’re interested in a standalone tank, however, we recommend visiting your local fish store or a pet superstore and finding one there.

Light

The Marineland LED Strip Light was affordable, but the body of the light was far too wide and dim to compete with the superior and cheaper Nicrew.

We also considered a slew of similar-looking, well-reviewed cheap aquarium LED lights from Coodia, Deckey, Koval, and Mingdak. But like the Nicrew model, none of those lights are made by companies known for aquarium goods, and they’re available for purchase only on Amazon. If you’re going to take a chance on an unknown brand, the Nicrew light is significantly cheaper.

Heater

The Marina Submersible Aquarium Heater is a good, affordable heater, but it's only marginally cheaper than the Eheim Jäger, and we think it’s worth paying the extra $12 or so for a more accurate and more precise model that’s widely known and trusted. Each number on the Marina model’s internal thermometer is marked in intervals of three or four Fahrenheit degrees (for example, 72, 75, and 79 are in sequence), and a sliding red band allows you to set the temperature somewhere in the middle of those intervals. Although this design allows you to set somewhat accurate temperatures, it’s not as precise as on the Eheim Jäger.

The Penn-Plax Aquarium Heater, though three-quarters the size of the Eheim Jäger, stood out much more due to the bright blue color of its internal thermometer.

Although the Tetra HT Submersible Heater remains the unshakeable best-selling heater on Amazon, it’s preset to 78 °F, making it an inflexible option that’s more vulnerable to manufacturing errors.

While we appreciated the Finnex Compact Electronic Titanium Heater’s external temperature selector, we struggled to find a place to put the controller where it would be easily accessible but not an eyesore.

The Aqueon Submersible Aquarium Heater had temperature markings only every four degrees, the same issue we found with its more indestructible twin.

Filter

The Marina Power Filter Slim S20 (for up to 20 gallons) remains the best filter included in a tank kit, but the small ceramic pebbles in its cartridges aren’t as large or powerful as the AquaClear filter’s larger stones, so get the AquaClear model if you're buying separately.

Pacific Aquarium’s Chi Cho recommended the versatile DeepBlue Professional BioMaxx Power Filter ADB88702 (for up to 30 gallons) as a runner-up to the AquaClear. This filter contains two deep buckets that can each hold one piece of foam and one cartridge, or any kind of custom filtration media. But unlike with the AquaClear model, the preset cartridges don’t include ceramic stones.

The Marineland Penguin Power Filter 150 stood out for its innovative Bio-Wheel, a rotating cylinder meant to maximize habitable surface area for bacteria. But the filter contains just one cartridge, which means your tank will cycle again when you replace it.

The popular Aqueon QuietFlow LED Pro Aquarium Power Filter and Tetra Whisper Power Filter are the same filters in those companies’ respective kits; both lack sophisticated, stable filtration because they rely on one cartridge.

The Fluval C-Series Power Filter’s five-stage filtration system looks just as effective as that of the AquaClear, if not more so. But those five parts (instead of the AquaClear’s three) all need to be cleaned and replaced on different timelines and are available mostly in aquarium specialty stores, so it’s more difficult to maintain this model well and procure replacement parts.

Water conditioner

API’s Tap Water Conditioner, Aqueon’s Water Conditioner, and Tetra’s AquaSafe Plus all have positive reviews and seem to work well, but they each treat only 10 gallons per teaspoon as opposed to Seachem Prime’s 50 gallons.

Fluval’s Water Conditioner has positive reviews but treats a meager 5 gallons per teaspoon; per ounce, it’s the second most expensive conditioner we tested.

Water test kit

Testing strips, such as API’s 5-in-1 Test Strips and Tetra’s EasyStrips 6-in-1 Test Strips, are a recently popular alternative to solution kits. After you dip these small tabs of paper into your water, they change color to reflect the test results. But currently a box of 25 strips will run you around half the cost of the API Master Test Kit—testing just once for pH, nitrite, nitrate, and water hardness costs around 50¢. On the other hand, testing once for pH, high-range pH, nitrite, nitrate, and ammonia with the API Master Test Kit costs just 16¢. Strips are also an all-or-nothing kind of test, as each strip contains colors for those five parameters. We like how the Master Test Kit allows you to test for just one compound at a time. In addition, since high ammonia levels are one of the most common downfalls of a tank, we think a good kit must contain an ammonia test.

We also looked at the Nutrafin Master Test Kit, a very professional-looking kit that comes in a durable carrying case and can test 10 water parameters. But at close to $100 at this writing, it’s an exorbitant buy for even for the most passionate water-parameter-heads.

Gravel substrate

When it comes to aquarium gravel, CaribSea’s Instant Aquarium freshwater substrate is in a league of its own. You can find most gravel for fish tanks sold in 1- to 5-pound bags that cost around $10. Buying enough of those other bags of gravel to fill a 20-gallon tank adequately is easily twice as expensive as buying one bag of CaribSea. Plus, during our research, most of those bags looked artificial or less elegant than our pick.

Soil substrate

You need two bags of Seachem’s Flourite Black to fill a 20-gallon tank, whereas just one of CaribSea’s Eco-Complete will do the trick. And one bag of the Seachem substrate costs as much as a CaribSea bag. Some owner reviews also say this Seachem substrate is better for aquariums that focus more on plants than on fish.

The popular Mr. Aqua Aquarium Soil has good reviews, but is sold in 1-liter bags that each cost around $17 currently, meaning you’ll need to spend more than $85 to properly fill a 20-gallon tank.

ADA’s Aqua Soil Amazonia also has great reviews, but you need four bags to fill a 20-gallon tank, and one bag currently costs nearly as much as a bag of CaribSea Eco-Complete.

Siphon

We looked into some other popular siphon models with different features, but none stood out as being quite as useful as the Terapump.

The snaking, 25-foot-long Python No Spill Clean and Fill Aquarium Maintenance System comes equipped with a nozzle that can attach directly to your faucet, allowing you to pump water directly from your sink into your tank. But we don’t recommend pouring untreated water directly into your tank; the toxic chlorine could shock your fish, even if you add conditioner right after.

The battery-operated Eheim Quick Vac Pro’s ability to suck out sludge without removing water sounds great for spot maintenance, but you’ll still need to remove dirty water one way or another.

Food

Many aquarists swear by Hikari’s Micro Pellets fish food, and we liked that it didn’t come as a flake. But this food contains just 43 percent protein, which pales in comparison to the 49 percent protein of our pellet pick from New Life Spectrum.

Pacific Aquarium’s Chi Cho also recommended Ocean Nutrition Community Formula Flakes, a food that has 48.8 percent protein but is hard to find online.

Algae sponge

If you’re at all tuned in to the algae-scraping community, you may have seen the innovative magnetic scrubbing pads that allow you to clean without getting your hands dirty. These cleaners work like a magnetic sandwich: Put one on either side of the glass, and you can then scrub from outside the tank without touching any water. Although these scrubbers do relieve you of much of the hassle of cleaning algae, they can end up scratching your tank: According to Cho, even one grain of sand accidentally wedged between the scrubbers can leave a zigzag of gouges before you even notice the damage.

We also looked at traditional scrapers, such as the Penn-Plax WZ20 Wizard Aquarium Scraper and Scrubber Combo Kit. But the stainless steel scraper looks unnecessarily harsh for normal algal growth, and some owners report that the head falls apart after some scrubbing.

The API Algae Pad for Glass Aquariums was particularly cheap, but we preferred scrubbers with handles so you don’t have to worry about sticking your whole arm into dirty aquarium water.