Detritus is a particulate waste product in your aquarium that you can see. It is produced by the waste products of food you feed your tank, plus the organic processes that occur naturally in your tank.

It looks like there is sediment or dirt on the bottom of your tank or your sand. If you stir up your aquarium sand, the sand will settle out fairly quickly because its heavier, but you can still see the detritus suspended in the water for quite some time. Eventually the detritus settles out again and your water clears up, often after several hours.

Often detritus is heavy with unwanted stored nutrients such as nitrogen, phosphates, and other waste products. These are the same nutrients that causes hair algae to grow. For this reason, its good to keep the level of detritus down to a minimum, especially with SPS corals.

If you can remove as much detritus as possible it will benefit your tank by lowering the amount of dissolved waste in your water.

I have no detritus but still have hair algae. Why?

Often a water test will indicate that you have no nitrates or phosphates, and yet you still have a hair algae problem. So whats happening?

Most likely, the dissolved nutrients in your water are being used by the hair algae, so your readings are zero. But the detritus is continuously feeding more nutrients into the water, which are then used by the algae, with the result that nutrient levels are STILL reading zero on the tests.

How can I get rid of detritus?

You can siphon detritus manually or you can use a mechanical (not chemical) prefilter to remove it as the water passes through the filter. .If you're using a canister filter, be sure to clean the actual filter often, or the detritus it collects will just decay even further, introducing unwanted nutrients BACK into the water stream.

Is detritus ever beneficial?

We have some coral farming systems that have a thick layer of detritus on the bottom and zero hair algae. However, these are heavily stocked SOFT coral systems. These systems are well aged, and very balanced.

We think that this works because the soft corals remove the nutrients from the water faster than the algae can get to it. Soft corals actually benefit from higher nutrient loads (to a certain point). Some softs will feed on the particles of detritus floating around in the tank. Others will use the dissolved nutrients that the detritus gives off continuously, as it maintains equilibrium with the water. Softs such as Xenias actually thrive on durtier water.