Protein skimmers - Yeah and Nay

I am a big fan of the use of a protein skimmer in any marine aquarium with fish only or a highly populated or new reef aquarium. A protein skimmer is a device that will remove various organic matter from the water, by bonding it with oxygen. The organics bond to the surface of the oxygen bubbles and are propelled up where they are collected out of the water column in a collection cup. The clean water travels to the bottom of the protein skimmer unit where it is returned to the aquarium free of the organics.

I have been quoted many times in the media as being someone that is against the protein skimmer. I want to clarify that this was never the case. I have always valued the protein skimmer but was one of the first to stand up and say that it is not always required and does have some negative effects worth noting. At this time it was believed that a skimmer was totally necessary for any reef aquarium. I didn’t believe this at all because while it can remove various organics, it can also strip the water of valuable trace elements.

To an aquarium run with bio balls, a skimmer does make a huge impact on the water quality. The bio balls break high-level waste into low-level waste or put another way, it turns something you don’t want into something else you don’t want. The skimmer, if placed before the bio balls, is able to remove organics before they are broken down by the bio balls into low level waste, which the skimmer can’t remove. The low-level waste will build up until it has negative effects on your inhabitants and increases your algae growth. It will also require more water changes. Placing the skimmer after the bio balls doesn’t make sense because the high-level waste has already been broken down by the bio balls before it gets to the skimmer. So in many cases all the skimmer is able to remove is your valuable trace elements.

The skimmer seems to be most valuable to new aquariums with unstable bio loads, but once the aquariums become stable (unless run with bio balls), there should be adequate bacterial allocation to ensure that your water quality remains high regardless of the use of the skimmer. At this point the cap can be removed from the skimmer and it can be viewed as an oxygen reactor. Please note that the amount of oxygen offered to a system is far less then logic would suggest, but is still better then nothing.

The presence of organic waste will have more of a negative impact on coral than the absence of trace elements so only remove the collection cup of the skimmer when the tank is stable, all the animals are thriving and you have conducted a three week skimmer test. Once the corals start to thrive and your water quality is high, trace elements become more of a limiting factor than the impact of using the skimmer. The skimmer will remove waste which is already able to be broken down by stable bacterial allocation.

The three week skimmer test is a way of testing the value of a skimmer to a system. The way I do a skimmer test is to not do any water changers or add any trace elements or other chemicals at all for three weeks. If you find at the end of the three weeks your skimmer is no longer pulling out waste, add a dose of trace elements. At this point the skimmer will start to skim again and prove to you that all it is removing is the trace elements that you purchased to add to your tank. It is this use of the skimmer that I have been vocally against.

Once you have done the three week skimmer test, you can also do a trace element test to see which of your choice of trace elements is most likely to be moved by the skimmer. With the skimmer running, try adding only one solution and see how much of it is removed by the skimmer in the next couple of days, then wait a week with the skimmer on before you add the next. By the end of this test, you will clearly see which solutions need to have the cap removed and which can be added with the skimmer working.

Many corals require the presence of various trace elements in order to thrive long-term. If these elements are lacking, with time there will be a cost to the coral. Some people argue that they don’t need trace elements but experiments have proven that their value is significant. This is easily seen in their reaction once they are added or after a water change is done. This thinking is similar to the person that says that they feel fine even though they have high blood pressure. Sure you are fine with high blood pressure now, next month, next year but with time there will be a cost. The removal of trace elements is the main downside to a skimmer, so I suggest every one consider getting a skimmer and use it while the tank is new, unstable or over-populated.

Tanks that are over populated will benefit by the use of a skimmer. In this case when you see the need for the trace elements but do also feel the need to have organics stripped from your tank due to the high fish loads, you can try a system of running and removing the cup on the skimmer. Since many trace elements don’t stay in solution from long periods of time anyhow, it is worth taking the cup of the skimmer for two days after the trace elements have been added and then returning the cup to the skimmer until the elements are added again, at least weekly.

Many other types of media are now available that can be used to remove organics which will not remove trace elements such as Bio Chem Zorb, Rowa Carbon and Purigen. These media can give very good results and I encourage using them all the time.

The use of a protein skimmer will also help to improve mechanical filtration as many particles, even parasites and algae spores, will be removed by the skimmer.

Some skimmer designs are far more effective than others. It is worth researching which one will suit your application and give the best results. No matter how good your skimmer is, the thing that limits its production most is how often the inside of the neck in the collection cup is cleaned. This doesn’t mean tipping out the collected matter, it means cleaning the inside of the neck where the fatty acids and bacteria grow and break down the organics, stopping them from going over the edge into the collection cup. The more often this is cleaned the more effective the skimmer is regardless of the design of the unit.

The idea when setting a skimmer is to have the white foam staying in the inside of the neck and the coloured foam rising over into the collection cup. The chamber should be white with bubbles but not with so many bubbles that they overflow out of the skimmer into the collection cup as white foam or escape through the outlet into the tank, filling it with micro bubbles. To set the skimmer, the aim is to have the coloured foam go into the cup and the white foam stay in the neck. To do this, open up the air valve to raise the foam in the unit and close off the air valve to lower the foam in the unit.

Ozone can also be added to various skimmer designs. Ozone will offer better water clarity and disease control, but it will reduce the function of the skimmer by often resulting in the accumulation of nitrate. I advise conducting research before adding ozone as residual ozone is toxic. As with any piece of equipment in this hobby, ozone has it place namely in commercial use.

I do feel an effective over-sized skimmer is a must on any tank housing sharks or rays, because they excrete a higher level of waste call urea which places a higher demand on the biological filtration of a system and is best removed using a large skimmer.

Protein skimmers have also been developed now for fresh water but are only common in significant koi ponds.

In summary, I believe a skimmer is a great piece of equipment that has many uses for all marine aquariums but they are not what I consider to be always necessary and do not need to be run all the time.

Good luck and enjoy

Paul Talbot