if you use biotabs your soil is a bit too loaded
I've never used these products but I've looked around a bit
humus should be added to all mix to "recharge" it and you need about 15%
so a 15% could work in light mix too
but 40% is a bit much
I would suggest, if you can, to add more light mix and have 15% humus and the rest light mix
I remind you that biobizz light mix is medium fertilized and can take a seed to the second week without problems
one last thing, perlite is mainly used for irrigation, while humus loads the substrate, an alternative is expanded clay pellets which add volume and help aeration