Staghorn Algae, isn't it lovely? I detest the stuff.
My algae was caused by too many WPG, which was easily solved.
What type of lighting do you have, what is your lighting schedule, do you use ferts?
Once we determined what the cause was (thanks everyone here for that!) I backed down my WPG and then did the following:
Manually pull off as much algae as you can.
Purchase Flourish Excel, along with an eye dropper and a plastic syringe. Dosing in your tank is a little tricky as it's smaller. Standard dose is 2 drops of Excel per gallon. (You can safely double the recommended dose without harming your fish)
Your tank is 10gl so that's 20 drops. In a small clean plastic cup count out 20 drops using the eye droppper. Then use the syringe to suck the drops up into the syringe. Make a note on the syringe where the *20 drops* line is. I'm not sure how many mils 20 drops is?
Then use the syringe to squirt the Excel directly onto the areas of algae in the tank. You can safely do this once every 24 hours. I normally run my lights for 12 on/12 off. During the period of my assault on the algae I turned the lights off for three hours in the middle of the 12 hour cycle, which means they were on for 4 1/2 hours, off for three, then back on for 4 1/2 hours.
The plastic syringe I bought was the type used for giving meds to dogs/cats. It was closed tip and you cut the end off for whatever size opening you need. Don't make the mistake I did. I cut too much off and the Excel just dribbled out. I had to go out and repurchase another syringe. You want a small enough size opening that you're able to "shoot" the Excel at the stubborn algae areas. Make sense?
In addition to spot treating with Excel I also purchased two C. siamensis. Since I added the two SAE's at the same time I spot treated with Excel it's hard to say if it was one or the other, or the combo that did the trick. Either way you don't have room for this fish in your tank and they are the only known fish that feeds on brush/hair algae. It's too bad the powers that be didn't make a dwarf species of this fish.
Hope this info helps...