First, thanks for everyone's comments. This is helpful. I'll try to address things as much as I can to keep the conversation going.
Unless there is no room, why don't you just run the Lifereef external and put it outside the cabinet? That's what I did. This will end the dilemma.
I don't have the option of running it external; must be in-sump under the tank.
The only way it could be done is to plumb the skimmer outside and because the tank/sump is already in place and due to it's current configuration, that's not possible. It's also not wise considering it's 110-degrees outside here in the summer. I don't have an external shed (nor do I have room for an external shed) where I can place all of this equipment. If I did, I would have.
With a 550gal tank you should have more than enough space to run the skimmer externally. Then you could have Jeff make you a custom skimmer like someone else was just posting with a much wider skimmer body.
I'm not sure why you reached that conclusion, but it's not true. See above.
I talked to Jeff about custom building a 30" skimmer with a wider body and he advised against it in this application. I can't recall all of the reasons, but I believe it was an air:water-volume (in skimmer) issue.
Also, so that I'm not misleading about what Jeff told me, Jeff certainly mentioned that there's an "old wives' tale" going around that you can't run two skimmers. He couldn't be certain whether running two skimmers would be successful or not in my application but he mentioned running two skimmers on his system with success in the past.
If you have both. Nothing will beat experience, I say run both and see what happens. If you run them close to each other (Where the pump draws water into the skimmer) one might out compete the other. But if you run them one at one end of the sump and the other far apart or at the other end of the sump they both should pick up organics as no skimmer will pick up all of the organics in one shot. There will always be some by pass from the water coming down from the main display to the sump.
From what I've read, it has worked for some. But, unfortunately for me, it seem (and makes sense) that those running multiple external skimmers--as oppose to multiple in sump skimmers--have success.
A local friend is running 3 skimmers on his 1400g tank with success and that's what convinced me to go this route.
Did you think his sump is an olympic sized swimming pool?
The pumps won't be that far apart.
There will be no difference (good or bad) what part of the sump they draw water from. They are competing for the entire tank volume. The amount of DOS in his sump is the same as what is in his sump (any part of it).
The footprint for the skimmer section is 23"x33" (water height is ~8") so, you're right; there's room but they'll be in pretty close proximity.
Probably doesn't matter much, but to put things in perspective, the total sump size is 56" x 34" x 20".
Also it is not like you have to worry about running it externally and it will be loud. There is no noise whatsoever.
Very happy to hear that these are quiet skimmers -- that was a major deciding factor.
Also, just because you are running it externally does not mean you have to have an external pump. You can still run an internal pump, however you will have to drill and install a bulkhead into the sump for your skimmer return.
If I had the ability to run it externally, that's exactly what I would have done.
For what its worth, I ran two BK Mini 180's side by side and they did not skim equal. The one closer to my water inlet in the sump out performed the other. I switch the two around and ditto, the same out come.
I think I read a post from you early on in this thread where you said that. How much water volume did you have when you were those two 180s? A single 180 should out perform my ATB Elegance 200 Pro. I'll try to go back and find your post but what was your solution if you couldn't fit one large skimmer under the sump?
What about feeding two SVC3-30s from a single pump? Does that change the analysis?
Some of this is hypothetical, I realize, and sometimes the only way to find out is to experiment to find out. Heck, isn't that why most of us found our way to Lifereef skimmers? At the end of the day, like Jeff says, "proof is in the cup."
