GrowCNanswered grow question 4 years ago What was your water pH?
It's been a long time since I pH'd Happy Frog runoff and I think mine was low as well. Not as acid as yours but if I recall it was closer to 5.8 or 6.
I haven't been too happy with Happy Frog. I bought a bag for sprouting and seeding and I don't get as good a results as using Ocean Forest. Then for the main grow I use 3:1 Ocean Forest with pearlite.