for down lemon juice,baking soda for up,for last resort to you get something better,check this out,new to the hydro scene so bear wit me,first i ph and ppm my water,nothing but water,so as i add each nutrient i document which rise and fall the ph and ppm,so i came to a conclusion and found a sweet spot ,when i add more food/8-16-36 my ph drops down but ppm goes up,mag-sulfate goes up,cal nit goes up,i keep the res right at 6 in the steaming heat,im using 5 gal mix every 2 days,so i mix at 5.8 and 1000 to 1025 ppm,that start,just refreshing the other 30 gal there,when i add to the res it csan go each way,so when it heat of day over 100 outside were res is ,the ph swings to 6 still were i want it,and the hydro guard also drops ph a little,but i dont go over the limit for once a week,i add 60 mil to the 33 gal can ,so you might be able to drop your ph with more food if it is what im using,but it will also add more ppm and you have to tweek it in between