Protein Skimmer: Ultimate Buying Guide plus 11 Reviews

Protein skimming removes dissolved and particulate organic matter by whipping the organics into a foam inside the skimmer. Protein skimming requires a lot of tiny micro bubbles to grab onto the organics.

The dissolved organics form a semi-ridged structure around the tiny bubbles and form what we call foam.

The goal is to create a stable, mostly dry “skimmate” foam. The surface tension of seawater makes it easy to stir up foam and skim it into a collection cup.

However, this is very difficult to do in freshwater due to the difference in surface tension of the water and nature of the dissolved organics. Protein skimmers are only used in freshwater where there is a very high level of dissolved organics in the water. These situations include high-density fish farms and heavily stocked koi ponds.

In freshwater aquariums, it’s easier and more effective to remove organics by making water changes.

Protein skimmers only remove “foamy” substances.

Nitrate is an inorganic chemical and is not foamy or “surface active.”

Nitrate cannot be removed by protein skimming. Organic pollutants containing nitrogen are broken down into simpler substances by bacteria in the aquarium. Nitrogen compounds eventually get converted to nitrate.

Protein skimming removes the organic nitrogen sources before they get converted to nitrate.

We can say that protein skimmers indirectly reduce nitrate by removing organic pollutants from the aquarium.

Phosphate test kits measure inorganic or “reactive” phosphate.

This is the type of phosphorous that stimulates algae growth. Inorganic phosphate also interferes with the growth of stony corals. Phosphate reacts with calcium and inhibits the corals from making calcium carbonate skeleton.

Protein skimmers cannot remove inorganic phosphate from the aquarium water because it is not surface active and can’t form a foam. Many organic pollutants contain phosphorous. As these organics break down in the aquarium, phosphate is released into the water.

Protein skimmers indirectly remove phosphate by skimming out phosphorous-rich organics before they break down into phosphate. Protein skimming prevents the build-up of phosphate in aquarium water.

Yes. Protein skimmers inject lots of microbubbles into the water inside the skimmer. The turbulence can speed up the transfer of oxygen at the water surface inside the protein skimmer.

As the water pours out of the protein skimmer and into the aquarium or sump, the water surface is stirred-up again.

Oxygen enters the aquarium mainly through agitation of the water surface. This can be inside the skimmer and when the water pours out of the skimmer.

The amount of oxygen increase is thought be relatively low compared to the effects of circulation pumps that move water inside the aquarium.

If you have ammonia in your aquarium water it cannot be removed by protein skimming.

A protein skimmer can only remove foaming organic substances. Ammonia is inorganic and non-foaming. Aquarium fish release ammonia from their gills. Solid waste from fish and invertebrates is broken down by bacteria. Some of this organic nitrogen can be turned into ammonia.

Uneaten fish and invertebrate foods will also be biologically decomposed into ammonia. The biological filter bacteria convert the ammonia to nitrite and then nitrate. Complex organic pollutants contain nitrogen. Bacteria break down the organics and ultimately convert the nitrogen into nitrate.

Protein skimmers physically remove the nitrogen-rich, foamy organics from the aquarium.

Skimmers reduces the nitrate loading in the aquarium by stripping out the organic nitrogen.

Yes. Protein skimmers remove nutrients from the aquarium water.

Nitrogen, phosphorous and other nutrients are “locked up” inside organic pollutants that are dissolved in the water. Tiny organic particles also contain nutrients and can feed the algae.

Protein skimming removes dissolved organics and particulate matter from the aquarium. This prevents the organics from decomposing and releasing algae-stimulating nutrients into the water.

Since algae need nutrients to live and reproduce, protein skimming helps to starve the algae by depriving them of food.

You’ll never totally eliminate algae from your aquarium. You can bring it under control by reducing nutrient levels in the aquarium water.

Protein skimming tips the balance toward less algae growth. Sometimes the skimmate collected in the cup will have a green color. This is because a tiny amount of algae cells got concentrated in the foam and sent to the collection cup.

This type of algae removal is insignificant and has led some to believe a skimmer remove algae. The real benefit is the skimmer’s ability to starve out algae and reduce the growth of stringy and suspended algae.

Yes. Fish, corals, bacteria and algae continuously release slime, dissolved organics and suspended organic particulate matter into the aquarium water. Your protein skimmer should likewise run continuously.

This minimizes the build-up or organics by removing them as soon as they are released into the water.

If the skimmer is only turned on periodically the water quality will gradually decline, then improve when the protein skimmer is turned on, then decline when it is switched off.

Avoid the water quality roller coaster by running your skimmer all the time.

Some aquarists complain of skimmer noise, especially if their tank is in the bedroom. Some protein skimmers are noisy due to their design.

If your skimmer is making loud splashing or gurgling noises try adjusting the air flow or placing a foam block under the water flow to reduce splashing.

Excess foam or wet foam can be corrected by adjusting the protein skimmer. Each brand of skimmer is slightly different, so be sure to read the manual first.

Make sure you have set it up properly. The first step would be to raise the skimmer collection cup height. Raising the cup allows excess water in the foam to drain away.

Wet foam loses its rigidity and falls back into the protein skimmer. The foam will become more fluffy and drier as it rises.

Look for less drier foam formation as it rises up to the cup. Also take a look at the air adjustment valve.

Too much air can sometimes force wet foam up through the skimmer body and into the cup. Turn down the air just a little and watch the foam for about 15 minutes.

Make any adjustment slowly until your skimmer is working the way it should. Every aquarium is different. There is no one setting or adjustment that works on every tank.

Don’t be afraid to experiment with the settings. It may take several days to get everything dialed in.

Brand new protein skimmers need to “break in” before foam starts to appear.

Lack of foam is common and may be caused by harmless plastic manufacturing residue. After a few days of use your skimmer will begin to make foam.

Many aquarists wait a couple of days before trying to make adjustments on their new protein skimmer. Once you see foam rising in the skimmer, start to fine tune the settings.

If your aquarium water is very clean, you may not see continuous foam formation. Sometimes skimmers don’t create foam for a few days. Its normal to see foam formation increase and decrease in some tanks.

If you suddenly see a lot of foam take a close look at your livestock. A dead fish hidden behind the live rock could be source of the organics in the water. An algae die-off can also release a lot of organics into the water and cause foaming.

Certain medications and water conditioners can increase or decrease foam production because they change the surface tension of the water.

Protein skimmers need to create fine micro-bubbles to capture the organics and whip up a foam. The tiny bubbles are very effective at concentrating the organics at the top of the skimmer as foam.

Today’s modern skimmer water pumps create microbubbles and feed them into the protein skimmer. Sometimes new protein skimmers release some micro bubbles into the aquarium for a few days.

As the skimmer breaks in, the bubble release often goes away. Some skimmer designs include a foam pad to break the bubbles when they exit the skimmer or have a way to adjust the water outflow to minimize bubble release.

Be sure to read the manual and make adjustments for the air and water flow if necessary.

If your skimmer makes a lot of micro bubbles, place a foam block under the water flow to capture the bubbles and allow them to pop before entering the aquarium.

In many cases your sump will have limited open space for a protein skimmer.

When choosing an in-sump protein skimmer, compare the manufactures dimensions with the space inside your sump. Many in-sump protein skimmers come with a matched water pump.

You may have to purchase a separate submersible water pump if your skimmer does not have one. Make sure your measurements include the space requirements of the water pump too.

Some manufacturer’s measurements only include the skimmer. Measure the height of the skimmer.

A skimmer’s “footprint” may indicate it will fit inside the sump but won’t fit under the cabinet! If the skimmer is too tall, you won’t be able to stand it upright under the cabinet.

You can cut out a piece of cardboard that is the same height of the skimmer to make a “test fit” before you purchase the skimmer.

If you’re using a water recirculation pump in the sump, be sure to include it in your space calculations.