You complete Guide to 75 Gallon Aquariums from Equipment to Maintenance

As you probably know, owning fish can be a rewarding and interesting experience, and when you upgrade to larger tank size, you can have even more of the same, although on a larger scale or with more fish. Keeping fish in an aquarium, while not the easiest thing in the world, is one of the most fun hobbies because there are so many different types of fish, and different aquariums and environments to go along with them.

Freshwater versus Saltwater Environments

You can create either freshwater or a saltwater environment in your aquarium, but freshwater is probably going to be your best option. There are more things to keep track of in a saltwater environment like the salinity levels, and so a freshwater tank is a little less complicated. If you want to keep saltwater or marine fish, we’ll cover some of those basics a little later in this guide. For now, let’s stick with freshwater environments.

If you want to be successful at raising and keeping fish there are some things to keep in mind when setting up. Once you have acquired the proper setup, you simply need to make taking care of your fish a habit. We’ll get to the habits that you need to have a little later, but first, let’s go over what you need to know to upgrade your fish keeping to suit a 75 gallon or larger aquarium.

Choosing a Location

If you are upgrading to a larger tank, the first thing that you need to worry about is location. You want to choose somewhere permanent because unlike your small tank, you aren’t going to be able to move this one around when you want to. Remember that a gallon of water is about 8 pounds, so a 75-gallon tank will weigh around 500 pounds. Unless you want to empty the water from your tank or risk destroying your tank, you don’t want to move it. Because of the weight, you also need to choose the right cabinet for it, and that means something commercially manufactured to hold an aquarium that size. Don’t use your mom’s old dresser with the side propped up with old textbooks or something you bought at your local thrift store.

Here are a few other tips that you probably know, but they are worth mentioning for new fish owners who happen to be reading this article. All of these apply to both saltwater and freshwater environments.

  • Don’t put your aquarium in direct sunlight because it will make algae grow faster. Also, don’t put it in a drafty area. Both things – too much sunlight and too much cold air can cause drastic temperature changes that can be harmful to your fish.
  • Try to put your aquarium away from the most traveled paths in your home. Having people constantly walking past your fish tank will cause your fish to get stressed out unnecessarily.
  • Don’t put your tank too high or too low for you to be able to do maintenance. You might think it looks great, way up there on the shelf, but if you have to get a ladder to do maintenance every time you are probably going to do it less often and your fish will suffer.

Essential Equipment needed for large Aquariums

Aquarium Filtration

The first thing that you are going to need for a freshwater environment is an aquarium filter, and you’re going to need it to have a GPH or Gallons Per Hour rating that is the proper one for the tank size that you have. For example, if you have a 10-gallon tank, you’re going to need a filtration system with a GPH of 40 or higher. For a 75 gallon tank, you’re going to need at least a 300. You should always go a little higher to be safe.

Many people employ a sump tank for their aquarium, particularly marine aquariums because there is extra equipment that can be placed into a sump tank. A sump tank is simply an extra tank that will allow you to place extra equipment and grow bacteria for biological filtration. As far as the actual filtration system itself, you can use similar setups to the freshwater filtration systems, such as a combination of biological and mechanical filtration.

You also have the choice of using chemical filtration along with the rest of your filtration system, but be careful that you know what you are doing because too much of the chemical can be harmful to your fish. You also have the choice of using protein skimmers for marine environments, which are devices that create bubbles that the harmful substances can cling to and be removed. Also, with saltwater environments, you are going to need something to move the water like a powerhead.

Our recommendation: AquaClear Power Filter

Tank Lighting

The lighting equipment differs between marine and freshwater aquariums. Freshwater aquariums should be a little warmer than those used for marine lighting, and the lights should be high enough to discourage algae growth. For freshwater, the recommended rating is 5500-6500 Kelvin. A few larger tanks come with lighting, others you’ll have to buy lighting separately for. You’ll want to keep your saltwater tank lighting a little warmer, but on both, you should base it on the type of fish that you are keeping. The recommended measurement for marine lighting should be around 10,000 Kelvins.

Our recommendation: hygger Full Spectrum Aquarium Light

Heating System

You’re going to need to keep water warmer, stable temperature for freshwater aquarium fish. That means that you don’t want temperature that fluctuates rapidly. You’ll need to keep an eye on the temperature with a thermometer and make adjustments when necessary. With a larger tank, you’ll want to have a backup heater as well as your primary heater in case of an outage, because you’ll be much more likely to have either larger, or more fish in the aquarium, which probably means more expensive to replace.

Our recommendation: Cobalt Aquatics Flat Neo-Therm Heater


Use aquarium safe substrates like sand and gravel or choose live plant substrate. The sand and gravel will allow beneficial bacteria to grow. Freshwater environments should have gravel substrate, and marine aquariums should employ sand or mud substrate. You can use live plants along with whichever type of substrate you are using.

Our recommendation: Glass Stone Artificial Pebbles

Backgrounds & Decor

The purpose of a background is to make your tank look nicer and hide the equipment that is sitting behind your tank. Decor like castles and tunnels are also useful as it keeps the fish from getting bored.

Water Conditioners

You need water conditioners to clean your tap water so that it is not harmful to your aquarium. A water condition neutralizes the chlorine in your water, rids it of any heavy metals and then ages it to create less of a shock to your fish when you introduce it into the tank.

Our recommendation: Seachem Prime Fresh and Saltwater Conditioner

Testing Kits

If you have kept fish before, you should already have these: a pH kit, ammonia, nitrite, and nitrate test kits so that when you cycle your tank you’ll be able to make sure everything is properly balanced. For saltwater aquariums, you are also going to need to test the salinity (or saltiness) of the water to make sure that it is the right amount for your marine environment fish.

Our recommendation: Tetra EasyStrips 6-in-1 Aquarium Test Strips

Maintenance of Your 75 Gallon Aquarium


Cycling is the process of bacterial growth in the substrates and filters – good, healthy bacteria that is. The bacteria turn ammonia from decaying food and fish waste into nitrite and nitrate. This is your nitrogen cycle or “cycling.” So, how do you remove nitrites and nitrates? By changing your water regularly. You also can use live plants to help with the cycling process.

You should already be familiar with cycling if you have owned fish before. If not, it is a good idea to test out your cycling process by adding ammonia manually. Start with about 5 ppm (test after 30 minutes or so) with the fish tank set up but the lights off. Wait a week after adding ammonia and then test nitrites, which should rise as your ammonia levels fall. A few weeks after that, nitrate levels will rise and nitrite levels will fall. Then, you can change out your water as practice and once you have figured out the process of cycling properly, you can add your fish.

Read more about it here: How to Cycle a Fish Tank.


You should clean the parts of your filter, and the rest of your equipment every few months, but only remove part of your substrate or equipment at a time, because you don’t want to upset the delicate balance of your fish tank. Remember, you need the bacteria that is growing inside your tank, and if you remove it, you need to replace it quickly with new bacteria.


As mentioned, you need to test the pH, the ammonia levels, the nitrite, and nitrate levels and keep careful track of your fish tank. For saltwater tanks, you also need to test the salinity, so you are going to need those test kits as well.

Optional Maintenance Equipment

If you want to make it easier to care for your fish, you might want to get some gravel vacuum units that can help you remove waste from your substrate. You will also need a couple of buckets for changing out your water – you don’t want to use your dishes – and you should also have a toothbrush for cleaning your equipment – again, don’t mix it up with your real toothbrush. Nets are also extremely useful if you need to remove your fish from the water. In fact, it might be almost impossible to catch your fish otherwise.

A Quarantine Tank

You really do need a quarantine tank if you want to be a successful fish keeper. It only takes one instance of a sick fish wiping out your entire population to make you desperately wish that you would have gotten one, so get one before it even becomes an issue. You want your quarantine tank to be outfitted with a heater and a sponge filter, and it should be cycled with some of the gravel from your main fish tank. Anytime you get a new fish, you want to keep them in the quarantine tank for up to six weeks (even if they appear healthy and are compatible with the rest of your fish) to ensure that they will not kill the rest of your population.

Lighting Timers

Lighting timers can help your fish feel more at home and less stressed since they need darkness at night and you may forget to shut down your lamps. Having a light on at night will cause them serious stress.

Automatic Feeders

This should go without saying. If for some reason you forget to feed your fish, your automatic feeder will take over and your fish will get fed anyway.


Leave a Comment