It has recently been brought to my attention the topic of nutrient control in a reef. I'd like to write up a quick little article on why its important to try to keep these elements low and why it could be detrimental to your reef. I'd like to explain it in a few easy question and answer type examples.

What are nutrients and where do they come from?
Nutrients, for lack of a better word is fertilizer. It composes of nitrate, phosphate, amino acids, and vitamins. It can come from various sources. Two main sources is from food and from the source water.

Why is it so important to keep these in control?
Fish are generally fairly hardy and can withstand copious amounts of nitrate in the water column. When nitrates approach 100ppm, this could be dangerous to the fish. Nutrients is far more detrimental to SPS (small polyp stony) corals and invertebrates. High nutrient levels could ultimately result in the death of the colony. It is also very dangerous to certain animals like sponges, and anemones. They have little resistance to bad water conditions and could ultimately die. In the wild these animals are NOT exposed to NH4. When an anemone dies, it could foul up your water very quickly causing a sudden rise in ammonia. The sudden rise in ammonia could kill the rest of the livestock in the tank. It could quickly spiral and wipe out everything in the tank.

Another dangerous result is a bacteria bloom. This could be rare because usually carbon is the limiting resource to allow a bacteria bloom. Bacteria will grow at an exponential rate consuming nitrates, phosphates, and carbon. The dangerous thing about it is, it also consume oxygen in the tank. If the outbreak gets bad enough, your fish could suffocate in the water. This is why I recommend a skimmer. It removes dissolved organics out of the water as well as oxygenate the water.

How do I deal with nutrients?
Easiest way is to do a water change. Be sure not to overfeed, and always take out uneaten food several minutes after the inhabitants have had a chance to eat. If you feed frozen food, make sure to strain the food as well as possible. Usually frozen food is packed in nutrient rich water to "enrich" the feed for the fish.
Setting up a refugium will help control nutrients as well as create a haven for pods to reproduce without fear of predators. Pods help eat detritus as well as provide fish with a little snack.

There are advanced techniques available to deal with excess nitrate and phosphates, which I will cover in a different article.