Internal or External Skimmer

[sn4k33y3z]

Which do you prefer and why? I'm thinking an external skimmer would make any maintenance a little easier, but would also take up a lot more room. I'd appreciate any pros and cons you all may be a ble to provide.

 

[skriz]

For larger or higher bio-load systems: external.

External are more powerful, easier to deal with in most cases, and keep heat out of the water.

For small or limited space systems: internal.

 

[sn4k33y3z]

Thanks! I didn't even concider the heat load... My footprint is rather small being I'm building a 93g cube. It would seem to me an external would be easier for servicing purposes. If you had the option of internal or external which do you prefer?

 

[acroholic]

A lot of it also depends on your equipment setup. My tank and sump are behind the tank in an unfinished area of the basement on a platform. I use an Alpha Vertex 300 internal on a 465 gallon SPS reef with about 30 fish. Heat is not an issue from the twin RD pumps, as the basement location is cooler than most. I also have a whopper big MRC sump with plenty of room for an internal skimmer.

What I like a lot about an internal is how it minimizes flooding and leak risk in case of over-skimming or if a leak at a joint develops. There are ways to minimize those risks with an external skimmer as well, however.

I would look at your overall available space and equipment needs, but definitely make sure your skimmer fits in your available space (vertically and horizontally) before buying. Many folks buy what they want and then find it does not fit in their sump or space under the tank in the case of an external. Make sure you can remove the skimmer cup for cleaning, etc, and you have enough space overhead to pull it for cleaning. Do you want to add a skimmer neck cleaner? You will need even more overhead space for that. Just some things to consider......

 

[sn4k33y3z]

Thanks for your advise! I learned a few things. One of which make me wonder, how often do skimmers get unbalanced and will "over skim"? I do not intend on adding a neck cleaner (so I think lol). You mentioned some other measures could be taken for preventing leaking risks with an external skimmer... Please do share.

 

[tony_caliente]

"What I like a lot about an internal is how it minimizes flooding and leak risk in case of over-skimming or if a leak at a joint develops. There are ways to minimize those risks with an external skimmer as well, however."

Couldn't agree more...especially over hardwoods or on an upper level floor.

 

[porpoiseaquatics]

Under a 93 cube, you won't have room for anything other than an internal. I ran the Reef Octopus DWNB 110 under mine and it worked like a charm. In your case, room is your biggest enemy in terms of what equipment you'll be able to use (this is unless you intend to place equipment outside the footprint of the tank).

 

[acroholic]

Sn4k33y3z;866034 wrote: Thanks for your advise! I learned a few things. One of which make me wonder, how often do skimmers get unbalanced and will "over skim"? I do not intend on adding a neck cleaner (so I think lol). You mentioned some other measures could be taken for preventing leaking risks with an external skimmer... Please do share.

I don't believe skimmers will overskim too often, but nearly everyone that has one has it happen at one time or another. For an external it can be a disaster/flood. With an internal, the bulk of the water goes back into the sump, but what usually happens is you get bubbles and water spray coming out through the vent holes in the skimmer lid, and you get salt spray all over the place in the sump area, which can be bad for any electrics you have under there, as well as being a general PIA to clean up.

One way of minimizing this is to use a skimmate collection container that has a float switch incorporated into it that turns off the skimmer pump if it fills too high. Avast Marine makes one:

http://www.avastmarine.com/ssc/do/product/proteinskimmers/Davy-Jones-Skimmate-Locker">http://www.avastmarine.com/ssc/do/product/proteinskimmers/Davy-Jones-Skimmate-Locker</a>

These type safeguards are great, but the only issue with them I see is that you can introduce a lot of extra fresh water into your system via your ATO if you have to wait until the external collection container is totally full before it turns off the skimmer pump. also, if you run a Nilsen, you can OD your system on kalk as well.

My collection cup is huge, so I really don't need an external collection cup, and I had a skimmer overfoam and spray water all over the equipment once, and so I incorporated a DA float switch into the lid of my skimmer. This avoids the issue of a lot of RODI being introduced and minimizes the risk of ODing kalk as well. If the skimmer cup gets too full, the float switch triggers an alarm on my RKE and shuts off the skimmer pumps.

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Another mistake I have made in the past with my internal skimmers is when I add water to the sump but forget to turn off the skimmer, raising the skimmer section water level, and the skimmer overflows because the water height in the skimmer section is increased. So I also have a float switch in the skimmer section of the sump, which when the water level in the skimmer section rises, it will trigger an alarm that turns off the skimmer pump.

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For an external skimmer, you could do the Avast collection container suttoff and/or do the skimmer collection cup float switch. You could also use one of the water alarms with a sensor under/next to the skimmer body that would give an audible alarm if trigered. There may also be ones that control an electrical outlet that could turn off the feed pump. What I would probably do with an external skimmer is have a shallow acrylic tray built or build one myself that has sides a few inches high that you could incorporate a float switch on, that the entire external skimmer would sit in. Then, if there is a leak anywhere in the external skimmer itself, the tray float switch would trigger an alarm, turning of the feed pump and the recirculating pump.

That was another benefit of an internal vs external skimmers I failed to mention previously: external skimmers generally use a lot more electricity than an internal because most of them use a feed pump as well as a recirculating pump in the skimmer itself. Internals don't need a feed pump.

 

[sn4k33y3z]

Wow... I'm gonna go read this like ten times and digest as much of this as possible! Thank you for clarifying several questions and raising new points I otherwise would have NEVER considered.

P.S That is a HUGE Vertex Skimmer! What are you skimming the GA Aquarium for Petes Sake LOL.

 

[acroholic]

Sn4k33y3z;866179 wrote: Wow... I'm gonna go read this like ten times and digest as much of this as possible! Thank you for clarifying several questions and raising new points I otherwise would have NEVER considered.

P.S That is a HUGE Vertex Skimmer! What are you skimming the GA Aquarium for Petes Sake LOL.

No problem....all learned from making mistakes, hehehe!

Skimmer is skimming a 465 gallon SPS reef. Alpha Vertex 300. Twin Red Dragon 1500 pumps.

 

[outdrsyguy1]

If I had an external skimmer, I probably would have had 20+ floods at this point. Things get stuck in the venturi, sometimes addatives will form hard crust at the venturi and reduce the bubbles causing a huge change in flow. Or for some reason your sump level goes up a bunch.
If I did external, I'd put it in a pan and put a water bug in the pan to shut off the skimmer on sensing moisture.