long green hair algea and lotts of it.....

[reddragon]

so i got back from Mexico yesterday and had a buddy looking after the tank for a couple of weeks.good place to tell you he has absuloutly no experience with a fish tank, but alls he had to do was water top ups cause i was letting the tank cycle and there was nothin in the tank. so i thought no problem.
when i got back there was 8 inch long green hair algea all over the back wall.when i was in mexico i was chattin with the tank babysitter on the computer and he said everything is good, " there is quite a bit of seaweed growing,but its not bad"(ha ha sea weed) so i was thinking a little bit not a whole forest.
i bought a scrapper tonight and scrapped it all off. i tried to catch most of it but it was impossible to get all teh little bits. i made a net strainer and waved it around the tank for half an hour trying to get it all.
Any thing else i can do to prevent it to come back?