Marine tank

First marine aquarium – size, location, sump, panel

Since you are reading this text, I assume that you’ve already waded through the article “Before you set up a marine aquarium” and I have failed to talk you out of setting up a marine aquarium. That’s fine… although, this part (and the next ones) do not look bright, either. I do all this on purpose with the welfare of the aquarium inhabitants in mind. I wish that this hobby was started only by people who are determined and fully aware of the consequences of owning an aquarium. In this part I will tell you what kind of tank to choose and where to put it because with the number of options available, it is very easy to buy the wrong glass. I will explain what a sump and panel are and why a marine aquarium should use one of these two.

I have set up dozens of different aquariums in my life, and I have kept well over a hundred. Therefore, the following advice will be purely subjective, and others will not necessarily advise you to do the same.

The location and furniture to put the aquarium on

From a practical standpoint, the aquarium should take a place you will often be able to enjoy it. After all, it is supposed to be for you. Putting it in the bedroom, garage, basement, attic means that you have to go there to watch it, clean it and feed its inhabitants. On the other hand, the aquarium can not stand in a place where it will be in the way. That’s obvious.

The ideal place is a bare wall or a corner in the living room, away from windows and the TV. Unfortunately, such a place is almost certainly already occupied by a piano, an exercise treadmill or your grandpa’s favorite chair.

An aquarium is a heavy object, so it should not stand on typical Ikea furniture. Not only will the furniture board swell from moisture, but it will also deform and the drawers under the aquarium will not close.

As for weight, remember that 100 liters of water weighs 100 kg, plus 3,5% for salt, plus 10% for glass. Therefore, imagine a fat uncle (or two or three of them) standing on some piece of furniture to decide whether a particular cabinet will hold up. On certain furniture, such as an oak desk, it is theoretically possible to place a small, square aquarium with a capacity of no more than 50 liters, but this is an individual matter. Larger aquariums, say over 100 liters, should have a dedicated cabinet that can bear the weight of the entire tank.

There are aquariums that can be viewed from the front only (plus two sides). Then the back of the aquarium stands against the wall and is painted black, for example.

Aquarium tank - peninsula
Peninsula aquarium

There are also double-sided aquariums which stand against the wall with its short side. In this situation, the aquarium can be viewed from two sides (plus one short side). A double-sided aquarium (called Peninsula) can be set up so that it splits the room into two parts. A single-sided aquarium, on the other hand, is more likely to be placed along a wall or in the corner of a room.

Marine aquarium with a sump or with a panel?

A marine aquarium can be equipped with a sump or a panel. Let me explain you what this is all about. Marine aquariums require a lot of filtration and additional equipment. Such devices do not look good in the coral reef tank. For this reason, all the required equipment is kept either in a panel or in a sump.

A panel is usually the back part of an aquarium separated from the main space by either black glass or an acrylic panel. All the necessary equipment, such as a skimmer, filter balls, heater, etc., are hidden in such a panel.

While the panel is an integral part of the aquarium. The sump is a separate small aquarium that usually stands under the main aquarium (hence the need for a dedicated cabinet with a rack). It is connected with the main aquarium with special pipes. I know, I know… it sounds terribly complicated, but it’s a very simple and very safe design.

Marine aquarium with a sump
Marine aquarium with a sump
Sump construction
Sump construction

If you are wondering whether a marine aquarium should have a panel or a sump. Personally, I wholeheartedly recommend the latter solution. It may be a bigger expense to start with. But believe me you will thank me for the convenience of having a sump. I can’t imagine a marine tank without a sump.

What size marine aquarium should I choose?

As for the size of the aquarium, there is one golden rule here. Choose the largest aquarium you can afford, taking into account the need for heating (1W heater per 1 liter of circulating water), lighting (1W light per 1 liter of the main tank) and supplementation. Unfortunately, the usual trend observed on various forums is quite opposite. Beginning aquarists often set up a tiny tank to “see how it goes, and then possibly change it to a larger one.” This approach is 99% a bad idea.

  • Firstly, although cheaper, a small aquarium is more difficult to manage than a large one.
  • Secondly, most of the equipment needed for a small aquarium will be useless in a large one, so you will have to spend cash twice.
  • Thirdly, a small aquarium automatically limits the possibilities when it comes to stock.

In my opinion, the minimum reasonable aquarium is a 200-liter one, and only if you really don’t have room for a larger one. These 200 liters tanks will already give you some possibilities, although only aquariums above 300-400 liters will allow you the real freedom.

Size matters

And don’t believe when they tell you it does not. I refer mainly to specific dimensions of the aquarium here, especially second hand tanks. Many experienced aquarists order custom aquariums. And that’s generally OK. However, be careful with these as you may have be problems with selecting lamps for such aquariums. Yes, you can combine several lamps, that’s not a problem but it won’t be the cheapest solution.

Therefore, while available space is not a problem for you, I would suggest buying aquariums of standard size measured in feet, i.e. 2 ft = 60 cm, 3 ft = 90 cm, 4 ft = 120 cm 5 ft = 150 cm. For these dimensions you will easily get the right lamps. A marine aquarium should also be deeper than a taller with the word “depth” being reserved in this case for the distance between the front glass and the rear glass so, for example, 60 cm deep and 50 cm high.

Is it worth buying a second-hand marine aquarium?

As we’re discussing the option of buying a second-hand tank, of course, it should be an aquarium designed for marine aquariums. Adapting a freshwater aquarium to seawater is not worth the trouble.

When you buy such an aquarium, be sure to take a look at the silicone. It should be smooth, uniform, without any bubbles. It is also best to view the aquarium while it is still flooded with water. Then you can best see if the silicone is of good quality. Besides, in a flooded and illuminated aquarium, all kinds of scratches are best seen. Yes, yes… such a crack may be invisible in a dry tank, but in a flooded and lighted one it can drive you crazy. Aquarists often brag about their aquariums on forums, so it is also worth reviewing these threads and assessing the age of the aquarium and how it looked before it was sold.

Marine aquarium size vs. stock

The two are strongly dependent on each other, so when deciding on the size of the aquarium, it is important to take into account what kind of organisms you will keep in it. If you decide to have a smaller aquarium, then you have to give up large and fast fish. The corals will also be questionable as they can grow to huge sizes. This topic is, however, much more complex and will require you to wade through the Internet forums to expand.

OptiWhite or float glass?

OptiWhite glass is a glass with low iron content, so it is free of greenish tint. It is said that you can better see the inside of the tank through it. Of course, it costs quite a bit more than regular float glass. Is it worth paying extra? In my opinion, not really, especially if the thickness of the glass is less than 15 mm, because then this effect is practically unnoticeable. And even if not, you will get used to it very quickly.

What background color?

There are two main standards when it comes to background color – black and blue. A black background gives the impression of greater contrast and boosts the color of corals. It also masks the dirty glass more, and this is important because cleaning the rear window can be very difficult. The blue background looks much more natural and gives a great depth effect. Unfortunately, only if the rear glass is clean. Any tarnish or calcareous algae growing on the back glass will greatly spoil the effect of the aquarium.

Where to place the weir in a marine aquarium

Let’s start from the beginning… A weir in a marine aquarium is a small, separated part of the aquarium, which contains the pipes and screws that connect the main aquarium to the sump. The weir is topped with a comb, through which water flows. In standard aquariums, the weir is usually in the middle of the rear glass.

Weir in a marine aquarium.
Weir in a marine aquarium

However, in Peninusla or custom-made aquariums, the weir is mounted on one of the short sides of the aquarium or in the corner of the aquarium. In the case of the peninsula, the side is irrelevant, since both long sides are transparent. However, if you are buying a second-hand aquarium, make sure that the weir on the side will match your planned aquarium arrangement in the living room.

Large aquariums may have two weirs at either end, while an aquarium with a panel has no weir (there are some exceptions), and the panel itself is mounted on the back of the aquarium (from the wall) in 99% of cases.


I’m certainly not done with the topic of choosing the first marine aquarium, although I hope I have cleared up the basic doubts. In the next part, I will try to discuss other basic equipment that you must buy for your new aquarium.

Bartek Stańczyk

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