Fighting Phosphate

Do we really have to |hate phosj so much, or is it just misunderstood?

By Andy Temay livtt tion

SKp aqua:

Any aquarist who has made it through a majll algaB bloom has a verympeCific opinion about phosphates: they are bad. This opinioAis often considered gospel in the aquarium hobby and is frequently cited in hobby literature and on various message boards. The underlying rationale behind this assertion is that algae need phosphates to grow. If there are no phosphates in the aquarium, then algae will not grow. Following this logic, the goal sESIlglbe to maintain phosphate levels at zero in the aquarium.

In a very practical sense, this rationale is true. If you limit the amount of phosphate in the aquarium, you will algae growth. However, this is a gross oversimplification and an explanation of the role of phosphate in the aquarium is in order.

Digging Deeper

An essential building block of life, phosphate is present in every living cell in every organism. phosphate is a part of DNA and RNA, forming an important structural element of those molecules. AdgBimie triphosphate (ATP) is used by all cells to create energy. Corals, fish and humans use calcium phosphate to build their skeletons. All living tissue contains phospholipids. Nitrifying bacteria depend on phosphate in the process of converting nitrite to nitrate. In short, phosphate is an essential ingredient to life itself.

Phosphate enters the aquarium primarily through food, although some aquarium additives, such as products to lower pH and sea salts, can contain phosphates. Aquarium foods, which contain matter from previously living plants and organisms, must contain some phosphates. The phos-

All life as we know it, including this Anthomastus sp., contains phosphate in some form. The question isn't whether phosphate should be present, but whether we should seek to keep phosphate levels in the correct range for our systems.

phates in the foods are consumed by the animals and enter the water column as part of the excreta of the animals. It can also enter the water column when animals die and their bodies decay. Once in the water column, algae and other plants can use phosphates as fertilizer. Bacteria also play a role, converting organic phosphate to inorganic phosphate, but algae and plants can convert them back to organic phosphates. This cycle repeats constantly in the aquarium.

Dead Weight

The problem is not phosphate itself. The problem is excess phosphate that can be used as a fertilizer for algae. The answer to the question of how much phosphate constitutes an excess amount is simple: not very much at all.

In the oceans, phosphate values near the surface are close to zero. In bodies of fresh water, there is a great deal of variance, often depending on agricultural activities nearby. For the aquarium hobbyist, however, the best option is simply to keep phosphate levels as low as possible.

The lone exception to this is the freshwater planted aquarium. In the planted aquarium, phosphate may actually be added as a fertilizer for the plants.

There are many different strategies an aquarist can take continued on pg. 69 FishChannel.com

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