I agree with Brad, I've seen enough "skimmer" talk in this thread. There is no reason to believe that a Berlin XL skimmer isn't handling the bioload in a 48g tank. Hell I've got a Berlin Classic HO skimmer on my 100g tank and it seems to keep up. :?
While I'm not arguing that the Berlin is comparible to the MONSTER becket oversized skimmers that many people on here have, it does do a great job when tweaked a bit. I run mine with a MAG 7 and will soon replace the stock venturi with an aftermarket Kent one. These simple upgrades help the skimmer to perform at it's peak, which should easily handle most bioloads on most tanks under 150g. Sure it's no big bad becket skimmer, but it's also not $400-$600! (only cost me $150 for the skimmer, $30 for a used MAG 7, and soon to be $30 for a Kent Venturi = $210 for a decent skimmer)
In my experience with hair algae, the main contributors have been phosphates and low alkalinity. I attribute the demise of my hair algae outbreak to my maintenance of high alkalinity with Kent SuperBuffer, dripping of kalk to precipitate phosphates, and maintenance of skimmer to maintain peak performance. I'm sure that my small refugium with caulerpa and assorted other algaes also contributed to the starvation of the main tank algae menace.
Like others have said to you Christy, don't panic as time usually sorts these things out. Keep adding your SuperBuffer to increase/maintain your alk levels, drip kalk or use phosphate sponge/guard to diminish phosphates and consider setting up part of your sump as a refugium with some caulerpa to help maintain low nutrient levels in future. And if you wish to get the most out of your skimmer, lose the Turbo pump and replace it with a MAG 7 and a Kent Venturi.
HTH