Advice on some Problems

[Hangfire]

Okay, I've had my tank up and running for just over one month now. All the parameters are good - ammonia is at 0, nitrate 0, nitrite also 0. I'm measure the phosphate level of my tank water, the water I'm using to top up, and my salt as a fresh mix and they all come back at 0 (or near enough). However, I seem to be growing a bumper crop of algae and I'm not sure what to do. I tried having the lights out for three days and it worked like a charm - all the hair algae died off and the algae picture below took it's place with a vengeance. Does anyone know what type of algae I'm dealing with? Does anyone know a good way to kill it off? Any suggestions as to what I may be doing wrong? I've done a partial water change two weeks ago and will do another one this weekend. There are no critters in the tank other than 5 hermit crabs and three snails - so over feeding isn't a problem. Thanks for any and all help. Oh, I've also got a picture of a flat worm - I can only guess that this is the bad worm, correct?