All skimmers make some level of noise however Deltec believe that relative to the performance that their protein skimmers are amongst the quietest on the market WHEN INSTALLED AND OPERATED CORRECTLY.

Here are a few reasons for noise and tips to getting your skimmer to run correctly.

MCE600 and MC500 Protein Skimmers

As these protein skimmers are compact in design and used on smaller tanks without a sump then they are the most prone to questions about noise as they do not have a closed cabinet as a sound barrier.

The pump on these models fits close to the two walls of the body of the protein skimmer to reduce the external dimensions of the unit. Unless the pump is firmly fixed in position as intended it has the possibility to vibrate against the plastic body and cause a noise.

The protein skimmer is constructed so that the pump is held solid in two places, 1 - by the inlet pipe at one end and 2 - by the sliding plate that jams behind the pump at the other end.

If you have a vibration noise then the first thing to check is that these are solid. The easiest way is to push down on the removable sliding plate, (the one that runs up the side of the waste cup towards the centre of the protein skimmer). If the noise goes away then this is the likely cause.

Much of the noise heard is not caused by direct vibration but resonant vibration. Resonance is when another item in the proximity of the vibration source which does not have to be in direct contact is caused to vibrate at a certain frequency due to the specific wavelength of the sound wave.

Using the screw on the sliding plate tighten it against the skimmer cup whilst pushing down the plate and this in most cases will sort the problem.

Models manufactured after 2006 are fitted with strip silicone feet which cushion the pump and reduce vibration noise.

For those running the skimmer in a bedroom please bear in mind that even a fly sounds loud in the quiet of the night.

There is now a sound dampening kit available for the MC500 and MCE600 models which can be retrofitted on earlier models manufactured before mid 2006. Please contact us for further details.

Other Models of Deltec Protein Skimmer

The other Deltec protein skimmers do not have the same compact design and generally run very quietly but can like anything with a pump still cause other things in the tank or sump to resonate. By moving the skimmer slightly or moving the item that is resonating then this can be removed.

POSSIBLE REASON 1 - a restriction in the air supply system.

As the air volume to the pump is decreased it causes the impellor to move forward in the body and rub against the front of the housing causing noise. This is particularly noticeable on Eheim pumps and can be simulated by closing off the tap.


  • Remove the orange tap and blow it out in reverse. Often a ball of dust and salt will fly out.
  • Carefully take off the black silicone hose from the venturi tube. Work it off from the end - do not just pull it off.
  • The most likely area for air reduction is inside the centre of the venturi tube which blocks up with a hard salt/calcium/dirt deposit significantly reducing the air volume. Take a fine drill and use it to work through the deposit scraping the sides of the pipe to remove this hard residue until it is all gone.
  • Reassemble and test and the noise should have gone.

If this is not the reason then at least you have properly serviced the skimmer. In the future it is a good idea to use the suction from the air tube to draw in a little hot water (not boiling) on a regular basis to dissolve any salt before it builds up to this level.


POSSIBLE REASON 2 - foreign body in pump


  • Strip the pump and check for debris or snails in the pinwheel.

POSSIBLE REASON 3 - worn bushes (Aquabee Models)

The rubber bushes on the ends of the ceramic shaft can become worn or shrink and reduce in diameter allowing excessive movement of the shaft and impellor which results in vibration, noise and ultimately wear of the pump.


  • Take the pump off the protein skimmer and remove the shaft and impellor.
  • Using only the shaft, put the rubber grommets on the end and test them in turn into the holes in the casing. The fit should be tight when you try to remove them and not just fall out. If it is tight which is the case in 99% of the time then it is OK.
  • Reassemble and test.

The bushes on later models are made from Red Silicone as it is a much more dimensionally stable material.