Question about ph levels of juice ~ interest is for absorption of nicotine
The reason for citric acid would be to swing ph levels from alkaline to acidic, but the lower the ph (acidic) less nicotine absorbtion, higher the number (alkiline) more absorption. Some think the more acidic the better the throat hit, but my experience is opposed to high throat hit.....too harsh for me personally. Most juices are in the Ph range of 4. to 6.5 more alkaline.
Sea water is about level 7. Adjustments would depend on what ingredients you are adding into your juice mix, and at what %. A person would need litmus tests to determine ph, available at pharmacies, pet stores that have aquarium supplies, etc. Tests normally use from 1 through 10, but specialty testing papers can go to much higher numbers, not really necessary for juicers. Snus users want highest ph possible, but again depends on additive flavorings you prefer.