tankanator, im sure that you readied my little problem to my large reef tank that due to the height of the stand that it would be difficulty to find a good skimmer to fit for that water volume and if I couldn't find one after I completed the changing of the lighting on both my tanks, I would have no choice but to change the stand and go through the extra cost of having what I wanted from the start.
Now the only difference from your 180 and my 240 is that the 240 is 2' longer and 60 gals more for on either of these tanks would I ever consider to use HOB equipment.
The huge problem you have there in buying a sump with an internal attached skimmer or skimmers is that you can do nothing into possible upgrades unless you change your sump for arrant the skimmer(s) that are in this sump you have has their own fitting slot that which they slide into?
On your idea of HOB skimmers, you will most likely be running two, if not three on this tank and with most HOB skimmers I knew about to do this is not an ideal plan for the long term of your tank.
Of course there be any HOB I not know about how its effectiveness be for ones tanks, but it does stand to reason when having so large a tank that your best to have a good size sump with the best skimmer to handle its bio load.
For if I couldn't find a skimmer that looked any good, I would change the stand as well, I was a while back trying to see if any skimmer at not taller then 24" for the tank in question for I had no idea of a skimmer to handle this would be able to fit well enough without having to make adjustments under the stand.
So you would do far better too change your sump and buy the best skimmer you can afford and on your water changes, I would do 30+ gals a week instead of every other week due to your bio load and such.
texan, There will be a SFE here and there that aren`t as bright in color as the next SFE and as your trying to say I think is that it means nothing of any ill health for the eel.