Pumps & Powerheads

Submersible pumps: These are pumps that can be fully submersed in saltwater. You can put them inside your sump or tank, but they must be FULLY SUBMERSED in water to operate properly.
External pumps: These are used outside your sump only. You install via a bulkhead from your sump to the pump, or with some up and over pipework and self-prime the pump. These pumps can not get wet. The main advantage to these type of pumps are durability and power. They have sizes for just about any size tank. Experts recommend turning the water of your tank over 5 to 10 times per hour in a fish-only system. In a reef tank, we recommend turning the water over least 10 times per hour (many hobbyist go up to 40 to 50 times/hour).
Internal/External: Obviously these pumps are capable of being plumbed outside the sump, OR can be plumbed internally with supplied fittings.
Circulation pumps: Circulation Pumps are typically added inside the display area of the tank itself to generate even flow amongst corals and rockwork. These units mostly have cages or fish guards on them so water is free to be dispersed in a broad direction rather than Power Heads, which are much more directional. They can also be added to Sumps to help stir up and remove detritus from dead flow corners. Most Circulation Pumps can also be connected to a "Wave Maker".
Power Heads: Power Heads are generally used inside the tank as Circulation pumps and/or Reactor pumps.  These pumps usually have hard return nozzles for very directional flow so you can connect them to Reactors, UV Sterilizers, or even Protein Skimmers via flexible hose.  They can also be added to Sumps to help stir up and remove detritus from dead flow corners.  Most power heads can also be connected to a "Wave Maker".
Auto Top Off Pumps: These are used along side of Auto Top Off control units to Automatically pump Top Off (R/O) water into a low level sump or aquarium system.
Dosing pumps: These pumps are used to automatically add supplements such as Cal, Alk, Mag, or even liquid coral foods to the aquarium in small, regulated and scheduled doses.
Wave Maker: Wave Makers are control units that are programmed to make the connected Power Heads/Circulation Pumps actually pulse to create a wave current. This adds natural flow to the aquarium and nicely benefits corals as well. Most Wave Maker units are usually programmable by pulsing every 5 or 10 minutes and even down to less then a second in pulsing intervals. These are available in the Wave Maker category.