As you can see above at day 7 theres pretty good coverage although there are white streaks both sides with no growth. At day one the nitrates were 5 and at day seven they are 2.5, while phosphates were 0.03 on day one and and day seven reduced to zero on salifert tests.
The coverage at day seven looks quite thick but there isnt really anything to scrape off yet.
How long before the first scrape?