AusBonsai

now my trident seeds have sprung and are showing signs of there first true leaves could i start to feed them some Seasol once a week? tho they are still in seed trays ill be separating them once the first set of leaves harden off.

Sure you can - but remember Seasol is a tonic not a fertiliser so you aren't really feeding them. Once a fortnight would be enough and you could do all your trees at the same time. Fertilisers will have a guaranteed analysis of NPK on the packaging.