All our salt water for our marine display is pumped directly from the sea. We have intake pipes which run under the road, across the Promenade and out into Galway Bay. This allows us to pump new, clean salt water into the aquarium at every high tide if we need to. We regularly monitor the water as we are pumping it in to make sure it is of sufficient quality to be used in the aquarium.

Once the water has been pumped into the building, it is held in the sea-water reservoir, and from there it is pumped into the system. However, before it reaches the main aquarium system, the water is passed through a system of filters to ensure it is perfectly clean and disease free. We have two main types of external filtration which we use here at Atlantaquaria, and between them these cover the three basic and most important forms of filtration: Chemical, Physical, and Biological.

This is a high-pressure filter full of specially graded coral sand. The un-cleaned water is passed through the filter at high pressure on its way into the system. The Sand Filter carries our Biological and Physical filtration.

Physical Filtration : As the water is passed at high pressure through the filter, any dirt or detritus in the water is trapped by the sand in the filter, and only clean water is able to pass through and out the other side.

Biological Filtration: living in the pores of the coral sand are billions of tiny friendly bacteria. These bacteria feed on a large variety of organic matter present in the water column, thus removing it from the water. This is a very important stage of filtration, as without this biological filtration, levels of ammonia, nitrates and other organic compounds could build up to toxic levels over time.

After the water has been through the sand filters, it is passed through what is commonly known as the “U.V. Filter”. This is a series of bulbs, which are surrounded by a thin casing through which the water flows. This is where the “chemical” filtration takes place.

Chemical Filtration: As the water runs past the bulbs, high intensity Ultra-Violet light passes into the water, irradiating it. This basically means that the U.V. light damages and kills any pathogens or bacteria in the water, meaning that the water is virtually sterile by the time it reaches the aquarium exhibits.

Water from the aquarium is continually being re-circulated through these filters, and their effectiveness increases over a period of time.

Exactly the same system operates for our fresh water display, except we collect our fresh water as a mixture of rain water and tap water. Before the fresh water is passed through the filters, it is allowed to settle in a large reservoir for a few hours, so that potentially harmful chlorine from the tap water can dissipate into the atmosphere.

Every tank in the aquarium, from the smallest fresh water to the largest Ocean tank, has an internal filter operating in it. The internal filters we use at Atlantaquaria are known as “air-lifted sand filters”. This is a very basic, but highly effective form of internal filtration, and works on a very similar principle to the high pressure Sand Filters mentioned above.

At the base of the tank is a grid of pipes connected together. Each of these pipes is cut with a series of small slits or holes, which allow water to pass through the pipes. On top of the grid lies the sand, coral or gravel which make up the tanks substrate.

The grid of pipes is connected to one or more vertical pipes, which run up the side of the tank to the surface of the water. An air-tube is passed through the top of the vertical pipe and down inside it. This air-tube is connected to an air pump, which pumps a continuous supply of air into the pipe. As the air bubbles up through the pipe to the surface of the water, it carries water with it up the pipe. As the water rises, this drags water from the grid of pipes into the vertical pipe to replace the water which has been dragged up. This in turn pulls water from the main part of the tank down through the substrate and into the grid of pipes to replace the water from there. As the water is pulled through the substrate, bacteria get to work, in exactly the same way as in the Sand filter. This continual cycling of water through the substrate in the tank acts as an excellent Biological and Physical filtration method, and is vital in keeping the tank hygienic, and the water crystal clear.