Green bubbly slime - help please

Evening everyone,

I'm new to the whole growing thing so need your help here please. I have seedlings in at the moment, which most of them started off in a un heated propagator. Thing is now I have taken the lids off, green bubble shaped  slime/ moss stuff had appeared all over the top of the soil. It doesn't seem to be spoiling the growth of the seedlings but I am a bit worried that in time it will. Oh I forgot to say that all of this is in my greenhouse. Any ideas? Should I be worried?

Also whilst on about slime, the water buts that came with my allotment are full of water, and also what looks like years of slime. Will the water be ok to use? Or should I pour it all out and give them a good clean?

Thanks is advance for any advice

The soil isn't too wet just dampish really, do you think I should be worrying about it? I think I might of used it on the seedlings when I first put them in. It looks like round rain drops just sitting on the top of the soil.

Good news about the water butts!

Thanks

Kitty - it sounds as if your compost was slightly too wet at one stage and because it was in a propagator and not getting enough air algae has formed on top of the compost. Although the algae should not cause any problems you need to ensure that your seedlings have good air circulation otherwise you may lose them through damping off.