Filtration For The Reef Aquarium
Filtration for today's reef aquarium is more about water movement than actual filtration. Many of the new aquariums come predrilled with overflows already installed. This configuration requires a sump mounted under the aquarium in the stand to catch the overflow water and pump it back to the tank. The sump typically has bio balls that the water trickles over for biological activity. The sump usually has room and chambers for mechanical filtration, carbon chambers, heaters, chillers, and protein skimmers. The pump can be external or inside the sump. Many sump filters have been replaced by refugiums. The typical reef aquarium has a water movement of about 10 times the gallons of the tank. For example a 100 gallon tank should have a water flow of 1,000 gallons per hour, but not all of this needs to go through the sump. Through the use of power heads you will be able to quietly and efficiently create a great deal of water movement. As a general rule, it is better to produce this current from multiple outlets rather than one strong return, reducing dead spots with little water flow.
Natural Filtration
Setting up a reef aquarium for natural biological filtration requires plenty of live rock and live sand. You need enough live sand to give a 2 to 4 inch bed, and enough live rock to build a wall against the back of the aquarium. Arrange the rock with plenty of ledges and caves to allow for good water flow and give fish and invertebrates a place to hide. We used to count on 6 weeks for the tank to cycle using bio media filtration, but when using live sand and cured live rock the cycle time is about 2 - 3 weeks. A good cleanup crew will keep your live sand free from algae, detritus, and other unwanted wastes. Commonly kept cleanup crew critters are red leg hermits, left-handed hermits, emerald crabs, sally light foots, turbo snails, and astrea snails.
Protein Skimmer
The main benefit of a protein skimmer is that it removes wastes from the water before it has a chance to break down. This is accomplished by injecting massive amounts of tiny air bubbles into a column of circulating water. As the bubbles rise through the column, proteins and amino acids cling to the skin of the bubbles. As these wastes build up, the bubbles become bigger and eventually overflow into a collection cup. There are three main protein skimmer types; air stone, venturi, and down draft. A venturi type skimmer uses a venturi valve to inject the air and eliminates the need to replace the air stones. They are also more efficient than the air stone protein skimmer. The down draft skimmer by ETSS is probably the most efficient skimmer for larger tanks of 100 gallons or more. The air and water is mixed by forcing water down a 2 inch column filled with bio balls. There are some people that argue protein skimming takes out trace elements along with waste and that you can actually over skim the water. It is true that protein skimmers do remove some trace elements, but this is minute and can be replenished through normal water changes and additives. Protein skimming benefits far out weigh any drawbacks and allow for a heavier bio load than otherwise possible.
Activated Carbon
Activated carbon removes many airborne impurities and heavy metals from the water. It also adds to the water clarity allowing light to reach the depth of the aquarium better. These inorganic toxins are absorbed by the activated carbon. Replacing the carbon on a monthly basis will keep many of the harmful toxins out the water. Be sure to use a high grade acid washed carbon for best results. Some cheaper activated carbons will introduce unwanted phosphates to the water.
