This is generally what pH up and down consist of.
pH DOWN contains orthophosphoric acid (H3PO4). The concentration is 81%, which is very strong so handle with care. Some other products on the market are considerably weaker so check the concentration before you buy. This is a very dense liquid and should feel much heavier than water.
pH UP contains potassium hydroxide (KOH). This is a very caustic liquid and should be handled with extreme care. Once again our product, at 25%, is stronger than some competing products. Always check the label for best value.
Personally I use coco with chemical nutes. I use the pH down mentioned above and to increase my pH I use POTASSIUM SILICAT.
PH adjustment though is dependant on your growing choice.
As already mentioned when growing organically pH isn't a real concern. Plants in general will survive between pH ranges of 4-8. Obviously there are optimums in this range for nutrient uptake.
J