How To Tune Your Protein Skimmer Like a Pro

A protein skimmer is an essential piece of equipment for reef aquariums that is designed to remove organic waste and dissolved proteins before they break down into harmful compounds like ammonia and nitrate. Through the process of "foam fractionization" the skimmer traps and removes dissolved organic compounds (fish waste), improving water quality and reducing the load on your filtration system. While it may seem like a complex device, tuning your protein skimmer for peak performance is a straightforward process that takes just a few adjustments.

One key piece of advice when turning your protein skimmer is to remember that "nothing good happens fast in a reef tank". Always give your skimmer time between adjustments, at least 30-60 minutes before making another adjustment. The following tuning approach is intended for internal venturi style protein skimmers

3 Important Variables For Adjusting a Protein Skimmer

Submersion Depth

Many sumps have adjustable water levels in the protein skimmer chamber. For most skimmers the submersion depth will be right about 8" of water but be sure to check the manufacturers specifications. You want to choose a skimmer that is compatible with the water depth of your particular sump. If your sump is too deep, you can use a skimmer stand to accommodate the water level requirements.

Foam Water Level

All skimmers have a foam level adjustment, typically a valve right on the drain. As you close this valve, it will cause the foam level to rise inside the skimmer body. As you open this valve, the foam level drops inside the skimmer's body. This adjustment does not affect the density of the foam, it really just negotiates how fast or slow you collect those bubbles in the cup.

Air Intake

The amount of air going into the pump affects the density of the foam and is the most critical adjustment. Most AC pump-driven protein skimmers do not provide a way to control airflow so you are somewhat limited to the minor adjustments you can make to the water level or add an air control valve to the venturi airline.

DC pump-driven protein skimmers allow you to control the pump speed which then negotiates how much air is being pulled into the skimmer and, therefore, provides you with a wider range of air tuning abilities.

More air bubbles = denser foam = wet skim
Less Air = less dense foam = dry skim

The Key To Tuning a Skimmer Is The Air To Water Ratio

When tuning a skimmer, it's all about finding the right ratio of air draw to nutrient level. Assuming the nutrient levels in your aquarium water are fairly constant, it's just a matter of tuning your skimmer to consistently pull the right amount of air and create the optimal foam density for maximum waste removal.

If your skimmer is constantly overflowing with fast-rising bubbles that fill up the cup very quickly with water, it's too much air for the amount of waste in your water. The microbubbles cannot retain their shape, they quickly aggregate, rise, and pop filling the collection cup with water. (most common issue)

If the foam head is thick, full of chunks, and not reaching your collection cup, it's likely not enough air for the amount of waste in your water. This is a pretty rare scenario considering most modern internal skimmers are quite efficient in terms of air draw. Raising the internal foam level is likely the answer moreover trying to increase the air.

Keep in mind that larger skimmers pull more air and if you cannot seem to stop your skimmer from overflowing regardless of water and foam level adjustments, it's probably oversized for your aquarium. An undersized skimmer, on the other hand, can be tuned to pull a stable foam head. The cup would just fill up faster and it won't pull as much waste as a larger, more appropriate skimmer would. Point is that everything starts with choosing the right size skimmer.

How to Tune an AC Pump Skimmer

Verify the water level in your sump is within the recommended range outlined by the manufacturer. You can raise your skimmer using a skimmer stand or pieces of louver egg crate.
Adjust the internal foam level using the outlet pipe to 50% open.
Let the skimmer break in for one week. During this time the skimmer will probably overflow or act erratically, this is normal. Rinsing a brand new skimmer in RO/DI water before installation will remove any oils or manufacturing residue and helps to alleviate these effects. Regardless, give it one week before attempting to really dial it in to be safe.
Most internal skimmers with AC pumps do not include an air adjustment valve and as long as you chose the correct size skimmer for your tank size, you shouldn't need to adjust the air. You can always install an inline valve on the airline should you wish to gain more control over the air intake.
- Large bubbles that rise fast and fill the cup with water = too much air (most common)
- Slow bubbles that fail to rise into the cup and cover everything in mud = not enough air (rare scenario)
Adjust the foam level to be even with the collar of the protein skimmer (where the cup meets the body of the skimmer). Give it an hour and if it collects too fast or overflows, reduce the foam level by 1" and evaluate again after 24 hours. Repeat until you are collecting waste as desired.

How to Tune a DC Pump Skimmer

Verify the water level in your sump is within the recommended range outlined by the manufacturer. You can raise your skimmer using a skimmer stand or pieces of louver egg crate.
Adjust the internal foam level to its lowest position, 100% open outlet valve.
Let the skimmer break in for 5-7 days.
Adjust the pump speed to achieve the desired foam density which is probably somewhere in the middle of the flow range settings. Slowing down the pump reduces the air draw. Speeding up the pump increases the air draw.
- Large bubbles that rise fast and fill the cup with water = too much air (most common)
- Slow bubbles that fail to rise into the cup and cover everything in mud = not enough air (rare scenario)
- If your aquarium is very new with minimal organic waste levels, reducing the air may be required to get the skimmer working consistently. If the aquarium is heavily stocked with higher waste levels, the skimmer probably won't require any air adjustments as long as it is properly sized.
Adjust the internal foam level to collect waste as desired. It's best to start with the foam level even with the bottom of the skimmer neck and let it climb into the cup on its own. If it collects too fast or overflows, reduce the foam level by 1" and evaluate again after 24 hours. Repeat until you are collecting waste as desired.