HI KEITH , Hold On, do you mean that you have only set this tank up for five weeks ? has your ammonia and nitrite peaked ?and disappeared ?.personally I think that that you have rushed into this. how long has the fish been in there? I think the last of your worries is the algea,get your self an ro unit and start doing regular water changes,While you are doing the water changes syphon off as much algae as you can without distressing the fish . If you cant purchase a ro unit yet ,go to your local lfs and buy some ro water,you can buy the water containers there to.I buy salifert test kits which I find totally reliable . do regular tests.Dont know if you've got a skimmer if you haven't buy one, by coral I take it you mean ocean rock looks OK in the beginning until it goes all slimy green personally wouldn't give it tank space, when funds permit get yourself good quality live rock excellent filter full of life see my pics (ps dont forget to aerate the ro water prior to use or when mixing up a batch of salt water IN YOUR CONTAINERS )NOT IN THE TANK)we all have to learn sometimes it can be disheartning and very expensive when things go wrong (see my thread ) Hope it all turns out fine for you all the best grandad.