Hmm,
Biothrive Bloom 2-4-4
Biobud .5-.1-1
Biomarine 2-3-1
Total NPK of 4.5 - 7.1 - 6
The NPK ratio's aren't to bad for week 5 of bloom, although I would only hit the P that hard once a week, maybe once in 2 strain dependent. Looks like the P is causing a tox condition (to much P). Roots Organic "original" is my guess for the soil, right?
The P in the soil, combined with the nutrient you use has to be the culprit. It is to much P.
No nute burn, no burnt tips. So the nutrition is good, except for the high P.
I see you want to be organic?
Let me suggest this as a starting point for an Organic water only soil. Simple to do and good instructions with options included. (This would be a homemade base for a supersoil, but most use a premix. The Rev uses FFOF as his base and I use Potters Gold as my base.)
http://forum.grasscity.com/organic-growing/1116550-easy-organic-soil-mix-beginners.html
Now for more advanced super soil type organic growing and for more ideas on how and what to use with the first soil, Read the Rev.s TLO book.
http://www.amazon.com/True-Living-Organics-All-Natural-Marijuana/dp/1931160961
Google TLO and read up, then get the book for the details.