Sand-associated fan worms
Illumination: does not matter.
Flow: very low to moderate, some specie tolerant of high flow and the ones pictured in this post have to be cleaned off my pump intake screen in the sump fairly regularly.
Buffering: does not matter.
pH stability: Don’t know. The specie pictured in this post will spawn in response to rapid pH swings.
Nutrients: does not matter.
Feeding requirements: IMO, a fanworm specie either will or won’t survive in your tank. Those that won’t often starve despite your efforts to feed them, so I would not bother. Those that will can sometimes spread at a shocking speed – another reason not to feed them.
Tank benefits: Fanworms filter POM, using digestable particulate as food, and using undigestable particulate to help build their soft tubes. Generally improve water quality and reduce detritus accumulation while placing very little bioload on the system – unless you feed them. If grown where they can be harvested, may be useful as export.
Tank considerations: Addition of phytoplankton or yeast can place a high nutrient load on the system. May compete with Tridacna for available POM.
Recommended resources: None.
Comments: The worms most seagrass-tank-people will want will build their tubes in soft sand. Trading with people who have them is the most reliable way to get them. These fanworms are preferential graze for some fish like Copperband butterflyfish which will eradicate them from a tank in short order. Other fish may pick at their fans and irritate them.
Fan worms growing in the sand in my tank. Even for tanks constructed solely to house plants, with low flow and elevated nutrients, these worms will likely do well. They also add some interest as the withdraw into and extend out from their tubes. A lot of visitors either don't notice or don't ask about by my coral, but almost all ask what the fanworms are. The grass in this picture is shoal grass. The green coral is branching hammer. A head broke off and fell onto the sand and has been spreading there for a while.