yeah, sorry i wasn't on last night, but Cinderella came out, and i HAD to watch it... I'm a big disney fan!!!
Dougie, that's probably red slime algae, aka cyanobacteria. You need to test your tank's phosphate levels. Also, testing is much easier this way: take a cup of your tank water downstairs with you, and do the tests with that. It's so much easier.
Whatever you do, don't dip the test strips directly in the tank.