Please see the FAQ below.

Here is a link that might be useful: There is something growing on my soil FAQ

Green algae doesn't actually harm the seedlings, unless it gets so thick that it seals the soil and no air can get through. Algae needs light to grow, when growing in pots you can top the surface with fine grit to keep it from forming. With those peat pots you would have to bury them. (but take that netting off!)

It seems like every store in the world sells those damn peat pots - which makes anyone new to seed starting think that they are the way to go, but they can be very problematic.

I haven't seen anyone on this forum use peat pots more than once or twice - almost no one who is experienced recommends them. If you are going to start again - get a bag of seed starting mix and use pots or plastic cups with hole punched in them. Uncover seedlings as soon as they sprout and keep that fan running. Tomatoes need to be transplanted to deep pots or 16 oz cups so that their roots can have room to develop.