External vs Internal Skimmers

[legalreefer]

I am looking at upgrading my skimmer for my 280g system. I have the luxury of running an external or internal skimmer. I’m running an ext skimmer now. I can’t run an internal skimmer in my sump but can always build a designated area with a constant water level if I were to go that route.

What are the pros and cons versus the two types?

 

[FutureInterest]

External skimmers allow you to adjust the amount of water going into the skimmer so you can dial it in easier, whereas an internal skimmer you really only reduce what's flowing out via the gate valve. The only other advantage of an external skimmer is that it won't be heating your water quite as much. The downsides of an external skimmer is that you have more seals that you need to ensure are solid so you don't get any leaks... and you have to plan for skimmer overflows. Every reef will run into it on occasion where the skimmer goes berserk... it could be an additive or it could be due to a snail spawning event... etc. When that cup runs over its not such a big deal with an internal skimmer but with an external you can drain your tank pretty quick.

 

[snowmansnow]

I've had both over the years... IMO internal is the way to go .. even if only for the overflow protection

 

[skriz]

Internal skimmers are subject to back pressure from the water they're sitting in. So, as your water level fluctuates, so does your skimmer.
Often times, you need to elevate the skimmer in order for it to work properly (check each model for the recommended water depth).
Pros: no plumbing required, small, don't need to plan for leaks or overflows.

External skimmers are generally much more powerful since they can use better pumps. Since they're not sitting in water, your sump water level won't affect the performance.
If you have a recirculating skimmer, you have much great control over the dwell time and performance.
Cons: plumbing, large so they take up more space, need to plan for leaks/overflows.

For large or heavy bio-load systems, you can't beat an external skimmer. For small systems, an internal is great.

 

[infpalex]

The thing is, every system is different... but I think it's the skimmer itself that matters. If you go high quality and one that is rated for your system... plus regular maintenance, you're good to go.