Burmeseanswered grow question 4 years ago Hi there, You have already known.Yes, lemon juice and vinegar.But I use egg shell with vinegar, where egg shell are crashed and stirring with vinegar.They are not only natural pH down solution but also my Calcium supplement.The best and last one is Coconut water.The best natural pH down solution with alot of benefits.I hope these might help you.Happy growing... ✌️