ciao, too much water my friend, you should give them less water, I usually touch the soil to check if it is dry or if I have to wait, you can also try to see if your pots are heavy or light enough to go with more water.
In my opinion you should try to give half a liter per plant when the soil is dry enough.
I also recommend you to give more bio grow like 2 or 3 ml per litre and start with bio heaven only when in flowering :)