Help on tomatoes in greenhouse please

Finally got my lifelong ambition of owning a greenhouse and had visions of everything taking straight away and growing like trifids. Except my tomoatoes (100s & 1000s, Sun Cherry and Sun Gold) have all had a poor germination rate and also started to devop a green algae? on the surface of the compost. Is this too much water on my part.

Hi Allen.
Here's some second and advic e.
I too have only just joined today and have the same problem!
I have had a few replies suggesting that i'm over watering (which causes the green stuff)
I was also advised to water newly planted seeds with tap water that has been stood for a while to lose the chlorine.
Hope this helps you as well as myself.
Good luck.
 Ricky.