How to take care of blackbeard and green algae?

[Andrew Puhr]

I have a 15 gallon. Decently stocked with small fish and shrimp and one female koi betta. It has some java fern, java moss, and a strand of guppy grass in the tank as well as duckweed. It gets about 6.5 hours of light per day. I dose easy green when I do water changes which is about every other week. I want to get the algae taken care of without damaging the other plants. I have some easy carbon but I am worried it will affect the other plants. 

[Jeff]

I would suggest some more plant mass - starting with fast growing stem plants - those will help you get a good start on it.

[JettsPapa]

I've had decent luck battling algae by adding more live plants (as @Jeff suggested), regular fertilization, reducing light to no more than six hours per day, manual removal, and regular water changes.  Instead of every other week, I'd recommend weekly water changes of at least 25%.

[johnnyxxl]

Anacris would help super fast stems.  You might also want to see what your nitrate level is 

[Pepere]

I agree woth extra plants, and extra fertilizing.  Weekly water changes.  Early on I would suggest deeper water changes along with gravel vaccing after cleaning walls and equipment snipping off algae infested leaves,(they ever so rarely recover) Clean sponge filter, 

increasing water flow is good too.  Adding an easy flow kit to your sponge filter gives a healthy flow boost…

water changes are not just for reducing nitrates…. Weekly water changes reduces dissolved organics.  

[Kurt Brutting]

When I have issues with algae I float Pearl weed until it creates a mat across the top of the tank. Or at least across a good amount of the top. 
It grows fast and soaks up nutrients like crazy.