Cabbage and Cauli seeds

I've got mould on both my seed compost (new brand compared to last year) and the multi purpose compost (same brand as last year). I'm ignoring it for now as the plants look fine, but I've never had it before.

Water seedlings from below (stand the pots / trays in a bowl of water, then take them out and let them drain, rather than watering from above)

Use tap water (rather than rain water).  Ideally let it stand for 24 hours before use (to let the chlorine escape), failing that make sure it is no colder than the compost - add a bit of hot water if necessary.

Include some fungicide - such as Chesunt Compound (although I think that has been phased out in favour of something else - which I have forgotten the name of)

I too have had this, but the bag says this is normal. Had what i think was a field mushroom too growing  its organic compost and the seeds see to be doing fine so im not worrying much