20 ml biobizz on 1.5 l water seems like a lot, maybe too much. I use algae flower from plagron and that's 5 ml/l/week tops.

If something goes wrong, it's probably overfertilization & overwatering IMO. When flowering you shouldn't water too much, 200 ml every 2/3 days? <===dunno for sure

I've had my share in plant problems what i've learned is, when you see that there is overnutrition, take some water, get the pH jùst right, i mean, on the exact level you want it to be, make sure it has the same temperature as the soil you're going to poor it on, and add only minor nutrients, i mean really minor. Few drops will do.

Water the plants with the "perfect water" and start upping the nutrient doses as you grow along. It has had it's results on my plants, they were having a near-death experience and they made it.

I hope all goes well, maybe some more experienced folk will have some more advice.
humbly yours, harv :thumbsup: