An empty marketing photo of a 20 gallon peninsula style glass aquarium tank with a rear filtration chamber.

Ultimate Guide to Setting Up a 20 Gallon Saltwater Tank

Updated 2024. Setting up a 20 gallon saltwater tank can be both aesthetically gorgeous and not break the bank.

We are shooting for around $800 with this build, but remember you don’t have to buy everything all at once… you can get one piece of gear at a time.

Our goal with this budget build is to strike the right balance between cost, aesthetics, and incorporating the latest gear. Additionally, we’ve ensured that this setup is as close to plug-and-play as possible, making it easy for you to set up and maintain your aquarium hassle-free!

If you want something that costs a little less, check out all of our setup guides here.

An empty marketing photo of a 20 gallon peninsula style glass aquarium tank with a rear filtration chamber.

Essential Items

The Tank

The Fiji Cube 20 gallon saltwater tank is slightly larger than our other budget builds, and is awesome because… well… because of it’s peninsula shape.

Having three large viewing panels means you can “see through” the tank and have a great view from different angles.  Peninsula tanks are some of my favorite, because it just makes everything more visually appealing.

As an AIO (all in one) style tank, the rear filtration chamber is where you will hide all of your gear.  This tank comes with a few things to get you started.

  • 1x 20g Fiji Cube Peninsula AIO Glass Nano Tank PRO

  • 1x Fiji Flow 300DC Pump w/ Controller

  • 1x Fiji Modular Media Basket

  • 1x Fiji 2.75″ Removable 200 Micron Filter Sock

  • 1x Rubber Leveling Mat

Still small enough that a sturdy desk, countertop, or table will hold it well, so you won’t need to splurge on an extra stand which will save you some money!

Here are a couple other peninsula style tanks to take a look at as well if you want something a little different.

infographic with a 20 gallon peninsula tank and a whole bunch of arrows pointing to the various features of the 20 gallon saltwater aquarium

The Perfect Light For a 20 Gallon Saltwater Aquarium

New lights for 2023, the AquaIllumination Blades have taken off.  They come in a lot of different sizes and in four color configurations.  The best general all around is the Blade Grow.  A mix of blues and whites, specifically designed for coral growth

What’s really handy about the Blade light, is it doesn’t need a mount because it comes with detachable feet that it directly on the rim of your tank.

For this 20 gallon saltwater tank, the 12″ Blade is the right size, and one will work just fine.  You’ll want to place this from front to back so you get the most light spread throughout the entire tank.

I’ve been using one on my 15 gallon HelloReef tank and it has been so good for my anemones!

closeup product shot of a 12" strip style led light with several blue diodes


For the most part, this Fiji Cube tank comes with the filtration you need to get started… mainly a filter sock.  But this system is super nice because it also comes with custom acrylic caddy with three levels, that you can use for filter floss, carbon, biomedia, gfo, or whatever else you want.

If you decide to use the filter sock, their system is nice because you don’t have to purchase a proprietary sock like you do with IM.  Just pick up one of the smaller 2.75″ size from HelloReef or Eshopps and it will slot right in.

Starting out, I would just use the filter sock, but pick up at least three more since you will want to change them out every 3-4 days, and it’s a pain to wash it twice a week.  I usually have around 8 for my system so I only have to wash them once every few weeks.

Gravel Vacuum / Siphon

Apart from using filters and filtration media, another essential part of aquarium maintenance is water changes. It’s a straightforward process of removing some saltwater from your tank and replacing it with fresh saltwater. During this procedure, you can also use a siphon to “vacuum” and remove any detritus, such as fish waste and leftover food, from the tank.

For this 20 gallon saltwater tank, I’d recommend the 2″ Pro Clean from Python.  The 1″ clogs too quickly for my liking. 

Here’s a video I made several years ago about how to start a siphon… without getting a mouthful of dirty saltwater!

Python 2" Gravel Vacuum on a white background


An essential piece of equipment for your saltwater aquarium is the heater. As mentioned earlier, stability is key to keeping your 20 gallon saltwater aquarium inhabitants happy, so a reliable heater is crucial.

Most saltwater aquariums house tropical organisms that thrive in a stable temperature range between 77-78 degrees fahrenheit. Unless your house maintains that temperature consistently, you’ll need a heater to ensure the well-being of your aquatic friends. On the other hand, if you live in a very hot climate, you might require a fan to cool your aquarium instead.

I have reviewed a ton of heaters over the year, but below is a beginner overview I made for BRS.

Based on personal experience, reputation, and cost, we highly recommend the Eheim Jager TruTemp 75 Watt aquarium heater. It’s a favorite among many saltwater aquarium hobbyists and remains budget-friendly.

Keep in mind that all aquarium heaters will eventually fail, so it’s wise to have a backup plan. Consider getting a second heater as a spare for emergencies. One thing experienced saltwater aquarium hobbyists know is the value of having backup gear!

If you’d like to check out some other heater options for whatever reason, take a peek at our Heater Gear Guide.


We don’t need anything fancy for this 20 gallon saltwater tank, just something that is easy to look at everyday and that keeps an accurate temperature.  The BRS Stick-On Thermometer just does that, and is about as inexpensive as they come.  I like to place my stick on thermometers near the rear side of the tank so I can easily check it everyday, but don’t have to stare at it!

A small stick on aquarium heater in cardboard packaging.
BRS Stick On Thermometer


A refractometer is a handy tool used by saltwater aquarium hobbyists to gauge the salinity of their aquarium water. They are highly accurate as long as you let the water warm up to room temperature before taking a reading!  You can also pick up a bottle of calibration fluid as well… that way you will know it’s reading correctly!

Or just pick up this BRS refractometer below and it comes with Refracto Juice… Just salt water pre-mixed to 1.026 salinity.

Starter Test Kit For 20 Gallon Saltwater Tank

Having a basic test kit is essential for any saltwater aquarium hobbyist. It proves most useful at the beginning of your aquarium journey, allowing you to test for the completion of the nitrogen cycle.

While this test kit may not be the absolute best on the market, it remains affordable and provides a ballpark reading that is suitable for most hobbyists. It serves as a valuable tool for monitoring your aquarium’s health and identifying any potential issues before they manifest as algae or bacteria blooms within the aquarium. Being proactive with testing can help you maintain a healthy and thriving saltwater aquarium.

front view of api saltwater test kit in original packaging. it's a semi-clear plastic box with a blue plastic lid. A label sticker covers the front, it's blue and yellow, and says API Saltwater Master Test Kit on it

Reef Rock

Rock plays a crucial role in every saltwater aquarium as it serves multiple purposes:

1. It provides a habitat for beneficial bacteria to thrive, aiding in the aquarium’s overall health.
2. The rock creates hiding spots for the aquarium inhabitants, giving them a sense of security.
3. It also acts as a surface for attaching coral, enhancing the beauty and diversity of your tank.

I really like this CaribSea Life Rock.  It’s human made and comes with spored bacteria to help cycle your tank.  This is also their Nano Reef Kit, which is 10lbs of rock with various shapes perfect for this 20 gallon saltwater tank.

There are a lot of other types of reef rock out there if this one doesn’t suit you, so check out our Reef Rock Gear Guide.

Three pieces of human made coralline colored rock against a white background

Algae Scraper

Hey there, let’s talk about algae scrapers – a basic but essential tool for your 20 gallon saltwater tank. No matter how well you maintain your tank, algae will find its way onto the glass. The good news is that a cheap scraper can easily take care of it without making a mess of your arms!

Using the scraper to remove the algae and then siphoning it out helps with the filtration, keeping your aquarium cleaner. In our budget build, we went with a regular hand-held option, but you might want to upgrade to the Flipper magnetic algae scraper for even more convenience down the line.

The handheld size is the least expensive, but you do have to get your hand wet every time.  So consider the 15″ size.  And be sure to get the stainless steel blade that is designed for glass tanks, not the one for acrylic tanks.

four different sized handheld algae scrapers next to each other on a white background

Fish Net

Having a net is a must for every saltwater aquarium hobbyist, and the best part is that they are incredibly affordable! It’s one of those tools that you’ll find indispensable.

Not only is it handy for catching and transferring fish, but you can also use it while thawing frozen food to remove any fillers or phosphates. The net’s versatility makes it a valuable and practical tool to have on hand for various tasks in your aquarium.

three different sized aquarium fish nets next to each other on a white background

Temperature Controller

Maintaining a stable temperature in your 20 gallon saltwater tank is crucial. Even the most reliable heating equipment can fail, leading to a complete aquarium crash.

However, you can avoid such disasters with a simple and affordable solution priced at just $35. This device monitors your aquarium temperature, ensuring it stays within a precise 0.1° F range and prevents your heater from getting stuck in the “on” position, which could boil your saltwater.

The best part is that this controller can also handle cooling tasks! In my case, living in the desert, I use a fan during summers to keep my aquarium cool. I plug the fan into the “cooling” outlet and the heater into the “heating” outlet, maintaining a constant 78° F throughout the year.

This impressive device also includes a built-in alarm, alerting me promptly if there’s a failure in the heater or fan. Remarkably, all these features come at an affordable price, making it an ideal addition to your budget-friendly aquarium build. 


Sand might not be a must-have, and some hobbyists are opting for bare bottom tanks these days. But, adding sand can really transform your 20 gallon saltwater tank into an authentic slice of the ocean. It not only enhances the aesthetic but also plays a vital role in biological filtration. Plus, it becomes a cozy hideaway and a source of food for certain creatures.

When it comes to sand, we recommend sticking with the CaribSea brand for the best options.

Check out our favorite aquarium sands here.

wet live sand for saltwater aquariums close up shot of 10 pound bag
Fiji pink sand in 20 lb bag with close up of grain size
clear bag of aquarium sand with CaribSea label and close up of grain size.
CaribSea Original Grade Ocean Direct

RO/DI Water Filter

The RO/DI filter is a water filtration unit that transforms tap water into nearly pure water through the process of reverse osmosis deionization. To understand its workings in detail, check out this video I made

While some online hobbyists might emphasize the necessity of an RO/DI filter for any saltwater aquarium, this claim isn’t entirely accurate. Although it offers long-term cost benefits and advantages, there are other simpler options for small and beginner saltwater aquariums.

One option is purchasing pre-made saltwater and purified water from your local fish store. Alternatively, you can use filtered water from a grocery store.

Over the course of a year, a $200 RODI filter will save you hundreds of dollars, so while it may seem a bit steep of a price to pay up front, it pays for itself rather quickly.

Here’s our RO/DI Filter Gear Guide.

BRS 4 Stage Value 75GPD RO/DI Filter System

Optional Items

Wavemaker For 20 Gallon Saltwater Tank

While the DC pump included with this tank will provide enough flow for a lot of things, including corals, getting a wavemaker will do a much better job, especially of creating turbulent water movement inside the tank, which helps to mimic the actual reef.

I’m a bit of a late adopter when it comes to the Nero 3, but I’ve been using it in my HelloReef tank, and I love it.  I have to turn it down a bit because at full full beans it’s a bit too much.  

My anemones have doubled in size in a few months, and they seem to love the flow this pump created.  

Plus, I now control my wavemaker, return pump, and blade light through the mobius app, so it makes things super handy!

close up product shot of aquaillumination nero wavemaker. It has a black case body, and green propellers. It's on a white background, with swirling water around it to simulate water movement

Salt Mix

Many saltwater aquarium hobbyists initially opt to purchase ready-made saltwater from their local fish store (LFS) due to the expense of buying distilled water from the grocery store and the complexities of setting up an RO/DI filter.

However, if you’re looking to save money and simplify your setup in the long run, mixing your saltwater at home is a viable option. With numerous salt mix varieties available on the market, I’ve personally tried many of them. While they all work well, their suitability depends on the specific inhabitants of your saltwater aquarium.

This Tropic Marin Salt is actually the one I use in all of my tanks. Check out this video below if you really want to learn more about salt!

You can also check out our Salt Mix Gear Guide for some other options.

product close up of white box of seawater mix from Tropic marin with an hand drawn image of a green coral with purple tips

Calcium / Alkalinity Test Kit

If your 20 gallon saltwater tank is primarily intended for fish or soft corals, you can relax about monitoring calcium and alkalinity levels. In such cases, regular water changes should provide the necessary nutrients and parameters these corals require.

However, if you plan to keep SPS (small polyp stony) and LPS (large polyp stony) corals, it’s crucial to maintain sufficient calcium and alkalinity levels to support their skeletal growth. This kit allows you to determine the ballpark values of these parameters in your saltwater, enabling you to gauge when additional dosing is required or if you may have been overdosing.

This is not my favorite test kit mind you.  Check out my favorite test kits in this gear guide if your curious. But this test kit will get the job done.

Maintaining proper parameters is essential for the health of your aquarium, even if you are diligently managing other aspects. By ensuring the right calcium and alkalinity levels for SPS and LPS corals, you create a thriving and balanced environment for these sensitive organisms to flourish.

Reef Tank test kit new in packaging on white background

Power Strips

One crucial piece of gear you might already have, or need to consider getting, is a power strip to accommodate all the equipment in your saltwater aquarium. While it may be tempting to cut corners here, it’s essential not to skimp on safety. Electrical accidents or fires are serious risks that should not be taken lightly.

Investing in a reliable surge protector/power strip is highly recommended. This particular option not only provides protection but also offers the convenience of turning off individual pieces of gear without having to unplug them. This feature is especially useful during saltwater changes, where it’s advisable to turn off the heater to prevent damage caused by exposure to air while still powered on.

By choosing a quality power strip, you can safeguard your equipment, ensure the well-being of your aquatic animals, and create a secure and efficient setup for your saltwater aquarium.

I do like this power strip, but my preference is to pick up a wifi version.

7 outlet controllable surge protector and power strip
Tripp Lite 7 Outlet (controllable) surgeprotector powerstrip

Magnetic Algae Scraper

Among the items in this affordable budget build, the Flipper magnetic algae scraper stands out as an exception. While there are cheaper alternatives available, none can match the performance and durability that the Flipper offers. Personally, I have been using the same Flipper for several years, and it continues to work flawlessly.

One significant advantage of the Flipper is its versatility. It allows you to switch between the stainless steel blade and the soft felt side without getting your hands wet, a feature that any saltwater aquarium hobbyist will appreciate. This magnetic algae scraper not only ensures efficient cleaning but also provides convenience and ease of use, making it a valuable addition to your aquarium maintenance toolkit.

For this 20 gallon system, you are right in between the Flipper Float and the Flipper Float Nano.  I would go with the larger size, but know that the magnet will be a bit strong, so you need to be really careful when using the stainless steel blade around the seams.  

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