What Are Phosphates?

Phosphate or PO 4 is a compound of Phosphorus (P), one of the top 14 out of 70 trace elements found in natural sea water that are considered to be essential for saltwater aquarium and reef tank systems. However, it is also a primary nutrient source for many forms of algae, particularly green hair species, so when high concentrations are allowed to accumulate in an aquarium, it then opens the door for aggressive algae blooms to occur.

Where Do Phosphates Come From?
Phosphates are introduced into saltwater systems in various ways, such as:

• By using unfiltered tap water for making up sea salt mixes or as top-up water.
• There are many common aquarium products used, such as some sea salt mixes, cheap activated carbon, KH buffers, foods put into the tank, and many other sources.

It is advised to pre-test tap or any other fresh water source, or new products used in your aquarium for phosphates, as well as nitrates. Why add more of something that you don’t need in your tank to cause a problem?

How Do You Reduce High Phosphate Concentrations?
The optimal phosphate level, especially for reef tanks, is an immeasurable one, or zero, with 0.05 ppm-mg/l being acceptable, and an upper level of 0.1 ppm cited as well. Having a good, reliable phosphate test kit is important.

Here are solutions for reducing high phosphate concentrations in saltwater aquariums.

• Adding limewater or kalkwasser solution has been associated with lowering phosphate levels. One of the theories why calcium hydroxide might produce better results than calcium chloride has been that the high pH and high calcium in a saturated calcium hydroxide solution cause precipitation of phosphate from the freshwater, eliminating this algae fertilizer from the solution.” there was a study done using calcium hydroxide to see what the rate of reduction of phosphates were. It is interesting that, when allowing the mix to sit, after two days there was only a 50% drop in phosphates, but after five days there was a 90% drop. The conclusion is that the drop in phosphates, when using calcium hydroxide, is slow and if the mix is used right away, any phosphates remaining in the mix will be pumped into your tank.

• Regular maintenance care routines with water changes are always recommended for a healthy aquarium. This helps to control phosphates, nitrates and many other unwanted chemicals elements and compounds in saltwater systems that contribute to water quality problems.
There are commercially available phosphate removing products, such as Rowa Phos, Aqua Medic Antiphos which are two of the leading products available in this country. You also find that it removes silicate from the water as well

• These particular phosphate removing products must be replaced every three months to keep the phosphates down at an accepted level.
One other way to remove phosphate naturally is to use a algae scrubbing filter (this is an area in your sump where you grow seaweed) which naturally feeds on the phosphate in the water. You then remove the excess alga that grows in the filter which has now fed on the phosphate with an end result of lowering phosphate levels.

Diagnosing phosphate in your tank.
The first symptom is normally filamentous algae, followed by green or red slime algae. You then get bleaching of corals as well as the corals and anemone shrinking.