Skimmers, are they really necessary?

[HBtank]

If the logical precautions are not taken, removing a skimmer will cause problems.
Marine aquarium basics tell us we have to condition the system for what is coming if big changes are planned. The remineralization capacity must increase to remove more DOC, the nitrification capacity must increase to remove more ammonia, the biological oxygen demand, BOD, will increase needing more oxygen, CO2 and ammonia production will increase. Without precausions it is not a good idea to remove the skimmer.
You need the skimmer because you use one. A system with a skimmer is not conditioned for not using one.
What if the skimmer suddenly fails?


Using AAM, active aquarium management, a balance between reducers and producers is found, the system will be able to adjust to any situation, with or without a skimmer in use, also in situations where the skimmer suddenly fails.

You had a problem after removing the skimmer. Only one?

Assuming you can maintain a perfect balance between reducers and producers is equally imprudent as assuming a skimmer will never fail. Biology is not that simple, there are all sorts of ways it can quickly be thrown off balance, such as an introduced pest or pathogen, just like an equipment failure.

There are many ways to tackle these problems and no single way is the correct way.

 

[ReefGeezer]

Assuming you can maintain a perfect balance between reducers and producers is equally imprudent as assuming a skimmer will never fail. Biology is not that simple, there are all sorts of ways it can quickly be thrown off balance, such as an introduced pest or pathogen, just like an equipment failure.

There are many ways to tackle these problems and no single way is the correct way.

I'm a big fan of attempting to balance users and producers in a strategic manner to steadily progress the tank toward maturity. The article here is based on that goal. Unfortunately, establishing and maintaining that balance is elusive. We are constantly adding producers and encouraging the growth of users to try to maintain that balance. Producers are easier to add than users, so the balance is often tilted and producing excess input... Particularly in new systems.

Employing a skimmer when the balance is tilted too far to the producer's side of the scale seems to me a great way to help ensure things don't get out of hand. On the flip side, switching off this carbon limiting device is important when the balance is under control.

I must also acknowledge a point made by @Belgian Anthias. Employing a skimmer delays reaching the balanced condition we are trying to attain. Personally though, I'm willing to live with that delay if the alternative is letting nature decide what nutrient users populate my tank. For some reason Nature seems to favor microalgae and Cyanobacteria rather than the sponges, tube worms, and planktonic and microbial organisms I would prefer.