Couple comments.
Turn your fan around so you are actually pulling air OUT. This is much more efficient, and the correct configuration for an indoor exhaust.
Are you commenting that MG soil contains a lot of peat or did you ADD a lot of peat? Peat is a useful soil amendment in sandy outdoor gardens, and to make mixes, but needs lime added as well at the time of mixing.
Your source water is a bit low, especially for use in a peat-based medium.

The switch from outdoor to indoor growing is especially difficult for nursery professionals. I have one for a consulting client, who ran a perennials farm his entire career, and has several significant and serious, but easily fixable, issues after making the switch. The shift in mindset can be painful! Luckily, cannabis is a great painkiller

Can you post up pictures of your seedlings, the area they are in, and a broad shot of the room as it is configured? Sometimes the answer is a big OH, DUH! when things seem right on paper, but something just isn't right.

Also, tell me about your watering style. You answered teh reservoir question- are you running automated drip? Seedlings should always be hand watered, and lightly!