First off what stage of growth are you in? Veg? Flower? How old is the plant?

But you shouldn't be fertilizing every time you water. Will torch the plants. And if it says 1/4 tps give it 1/8 tsp the first few times and then work it up very slowly. Some people don't ever get to max strength as it starts to burn the plant. Of course you can only learn that little fact after you've already burnt it.

As for pH? Water and soil should be around 6.5 to 6.8 for MJ. Over or under that it begins to lock out ferts. And you should adjust your pH right before you water. If it sits for awhile it'll go back up...which you discovered.