Marine Aquariums - A Beginner's Guide

Dan Everton's guide to keeping a successful and beautiful marine aquarium, including everything you need to know about setting up your aquarium, making your own saltwater, fishkeeping and live rock.

Created by Dan Everton on Tuesday, 4th of March, 2014.
Updated on Thursday, 20th of June, 2019.

Marine Aquarium and fish.

This is a beginner's guide to creating a saltwater marine aquarium and how to maintain the tank as a healthy environment for fish and live rock.

Setting Up Your Marine Aquarium

When setting up a new marine aquarium you will want to leave it with live rock, substrate, salted water and your equipment running for a minimum of 3-4 weeks before adding any live stock.

This gives the aquarium time to cycle and any die-back from the live rock can happen without causing water problems which would potentially harm fish or corals.

Once you do begin to introduce fish and corals this should be done slowly over a period of time to prevent a crash which can be costly and devestating.

Salt Water in Your Aquarium

In your marine aquarium is salt water, this is vital for the survival of your fish, corals and invertebrates as it is the same as their natural habitat where they would be found in the wild in the ocean. Over time your water will begin to evaporate and when it does the salinity (salt levels) will rise because the salt will not evaporate, so you will need to top the aquarium to keep the salinity levels balanced.

There are different salinity levels which people choose and this can differ depending on the type of tank you want to set up or have. If you have corals you are going to need a slightly higher salinity level than with fish only marine set ups.

You can mix your own saltwater following the instructions in our How To Make Saltwater blog rather than purchasing it. If you do want to buy, we currently offer three levels of salinity and these are 1.022, 1.24 and 1.026, for advice speak to our Aquatics team on 0121 355 7701.

Marine Aquarium Water Changes

25 Litre Jerry CanIt's recommended that you perform a 10% water change every week or a 20% water change every two weeks, whichever is more convenient for you. When you do this you will be removing saltwater and topping the tank back up with saltwater only, not RO water.

The reason for this is because unlike evaporation which leaves salt in the tank still, a water change removes saltwater so you need to add saltwater back in. If you only add RO water the salinity levels will drop causing problems.

We always advise that you invest in your own jerrycans, one for RO and one for saltwater and label them appropriately, that way you'll always have one free for the type of water you need and on top of that you won't contaminate one with the other.

You'll also find that aquatic stores will stock RO water, saltwater and loan out jerrycans if you do not want to buy one or make up your own water. 

Live Rock

Live Rock is the foundation of most great Marine aquariums. It is harvested from the ocean around the world from collections near reefs, where parts have become detached from the main body of corals due to storm damage.

It is highly valued in the Marine Aquarium trade and this is due to the fact that it brings a huge diversity of life to a closed marine environment.

Hosting nitrifying bacteria required for the nitrogen cycle that processes waste, live rock will also function as a superior and main biological filter system in your saltwater aquarium rather than using a traditional fish tank filter.

Live Rock also has a stabilizing effect on the water chemistry too, keeping a constant pH level by releasing calcium carbonate into the water.

How Much Live Rock Should I Use?

If you are using it as your main biological filter then we normally advise to use a quantity of 1 kilogram of live rock for every 9 litres of water. You can add extra into the tank though if you would like but you must make sure that you have a sufficient flow around the rock to prevent "dead spots" which could cause a water quality problem.

When you add corals to your tank they will become attached to the live rock becoming their base, and it is also frequently used as a shelter for marine inhabitants giving them a better quality of life.

With your live rock you can build caves, overhangs, arches and other areas which can give your aquarium an awesome effect, this practice is known as aquascaping.

Cure Your Live Rock Before Installation

Before installation in the tank live rock should always be cured, this is because a lot of the organisms which enjoyed living on the rock in the ocean will have died off during the transportation process. Failure to cure your rock properly can lead to a spike in your ammonia levels which can be fatal for your aquarium.

You can cure your rock by leaving it in salted water isolated from the main tank for several weeks, however most aquatic stores will have already done this for you.

Buy Live Rock for Home Delivery

If you would like live rock for your marine aquarium then please view our Live rock page.

Feeding Your Marine Fish

I always try to feed our marine fish frozen food, this is because it contains lots of nutrients and the TMC Gamma Frozen Food has been gamma iradiated to remove any impurities which could cause problems for fish. If you're not careful these nutrients can increase phosphate and other levels.

The best way I have found is to defrost the food in a small tub of RO water and then once it has defrosted fully net the food and let the excess waste water drain out, this means less uneaten nutrients disrupting the levels in your tank.

Adding New Livestock

When buying any new livestock it will usually be sold to you in a polythene bag in the UK, this makes it easy to transport. New stock need to be acclimatized, this allows the water to reach the same temperature as it's new aquarium and the best way you can do this is by dropping aquarium water into the bag containing your new stock. Eventually the temperatures will be equal and this will prevent shock to the fish or corals which can kill them so this process is very important.

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