If your return pump is the heart of the aquarium, then the protein skimmer is probably comparable to its digestive track. Protein skimmers churn water while being fed air chopped up by its pump's impeller to produce microbubbles. Dissolved organics or protein from uneaten food, animal waste and bacteria are drawn to the bubbles, creating a foam that rises up in the skimmer and deposits into the collection cup before getting the chance to break down into nitrates and phosphates. They all work in this general manner, but with the advancement in the reef hobby over the years a few different protein skimmer types have been developed to suit your needs or tank setup: Hang-On-Back, In-sump, and External - let's discuss.

More on what a protein skimmer is and how it works, here.

HOB Types of Protein Skimmers

Different models of HOB types of Protein Skimmers

Hang-On-Back a.k.a. HOB protein skimmer types do just that, install by hanging on the back of your aquarium. With these type of skimmers, marine tank filtration gets a boost with the added benefit of adding more flow to the tank. They are perfect for smaller aquariums with no sump. They also work great on all-in-one tanks, allowing more room for media or reactors in the back filtration chambers. Just know that the tank rating should be considered when choosing an HOB.

HOB Installation Tips:

Infographic of requirements needed to install HOB types of skimmers

  1. The space needed behind the aquarium to accommodate the skimmer footprint.
  2. The tank height should be tall enough for the skimmer to hang without interference from the stand, unless it is flush with the back of the stand.
  3. The skimmer mount should also be able to fit the rim thickness of your tank. If a tank has a plastic rim, it may need to be modified.
  4. Many of HOB skimmers do need to be primed before operating by filling them with water. Most will also need to be re-primed, if they lose power.

In-sump Protein Skimmer Types

Different models and styles of In-Sump types of Protein Skimmers

In-sump skimmers are the most popular type of skimmers. They sit inside the water within a sump in a cabinet under the main aquarium display. These skimmer types also include some nano skimmers which fit in the back filtration compartments of all-in-one tanks, like the Reef Glass Nano or the IM Desktop Skimmer, mounts inside the display tank. An internal protein skimmer has two main benefits: ease of setup and no leaks, but has the drawback of being reliant on water level. An ATO (auto-top-off) system should be used to maintain a constant level in the sump for efficient skimmer operation.

In-sump Installation Tips

Infographic of requirements needed to install in-sump types of skimmers

  1. Sumps typically have a designated skimmer section with provided dimensions. A skimmer's footprint should fit within those sump dimensions.
  2. In-sump skimmers have a recommended water level for them to run properly. A skimmer stand may be needed if your water line in the sump can only be run at a higher level.
  3. Another dimension to be considered with in-sump skimmers is its vertical height. Vertical clearance is needed to remove the skimmer cup for maintenance when the sump is inside a cabinet due to the limited space underneath your tank.

External Protein Skimmer Types

External Protein Skimmer

Not as popular as the others, external skimmers are mostly seen installed on larger (like, really large) tanks and public aquariums, but some like the Reef Octopus Classic 150 EXT are still available for "smaller" tanks. These types of protein skimmers do the job just as well, and have the benefit of not being reliant on a specific water level. They have one or more recirculating pumps with a venturi that mixes the air and water, while being fed by a separate pump. Using a drain tube is highly recommended with these types of protein skimmers, if you don't want any skimmate on your floor.

External Skimmer Installation Tips:

Infographic of an installation example for external protein skimmers

  1. Extra plumbing and a feed pump that can handle the head pressure of sending enough water to the skimmer will be needed.
  2. Depending on the strength of the pump a ball valve may be needed to raise and lower levels in the skimmer with the aid of the skimmer's gate valve.
  3. Installing the skimmer at an elevated level makes it independent from the water level in the sump.

Skimmer Maintenance and More Tips:

  • Choosing the correct rated skimmer for the volume of water running through your aquarium is key. Too small, the waste will need to be discarded more often or may overflow back to the tank. Too big, and the skimmer can sit idle from stripping the water of dissolved organics quickly consuming more energy than would otherwise be needed.
  • When new, rinse the skimmer under warm water to get rid of leftover manufacturing residue. DO NOT USE any soaps or chemicals to clean.
  • Allow new skimmers to break in by opening their outlets fully. This lets protein build up on the inside of the body, making it easier for waste to transition to the collection cup. This can take from 2 to 4 weeks.
  • The collection cup should be emptied prior to being full, so it does not overflow waste back into the aquarium. This is typically done about once a week for equivalent rated skimmers to tanks, or multiple times for underrated skimmers. The time it takes for a collection cup to fill up can also be affected by bioload, how often filter socks/pads are replaced, feeding regimen, additives/supplements, wet skim vs. dry skim, and more factors. The neck of the skimmer and body should also be cleaned during this time.
  • Calcium and algae buildup can reduce pump performance, so we recommend the skimmer pump be cleaned every 3 to 4 months. Remove the pump from the skimmer and disassemble all the parts, including: impeller, ceramic bearings, and covers. Once taken apart, they should be soaked in an aquarium safe cleaner like Sicce Pump Clean or a vinegar/water solution. After soaking the parts should then be scrubbed of any residual buildup.
  • Air lines, silencer and venturis should be kept clean at all times from salt creep or any other elements that may clog the airway. Clogs will reduce the performance but can usually be cleared out with some warm water and scrub with a pipe cleaner.
  • Overflowing can be caused by a change in water viscosity, leftover manufacturing residue, uncycled tanks or factors like added: additives, epoxies, oily foods, medications, etc. To stop the overflow the most effective ways are to add extra carbon to the system or perform a water change. Also, check that the water level in the sump isn't too high.

"Skim skimmer, who wants to keep their tank cleaner? You and I...." *Beenie Man voice