Chasing my pH tail. Lol

Just get an “inorganic” pH down.. like GH ph down. The problem could be as described by others, but most like the problem is the vinegar or anything organic like that that cuz it will degrade quickly over time in solution. I tried lemon juice my first ever hydro set up and had the same issue. Products like GH ph down will hold steady at the pH you have adjusted to MUCH longer when everything else is on point.

Yeah, don’t use vinegar. Most nutrients are acidic. What enzyme are you using? Or even PH down—- but don’t use vinegar! Keystone grow has some products like silver rabbit that would be perfect to stabilize

Hydroponic setups are likely to see pH levels rise over time, as the system becomes more alkaline. Why? Most nutrients are slightly acidic. As the plants absorb these nutrients through their root systems, the system slowly loses its acidity to become alkaline. Over time, the pH numbers will gradually rise until you add more nutrients. Temperature also affects the pH level of water. As the water warms up, it slowly releases CO2 into the atmosphere, which naturally increases pH levels. The strength of your nutrient solution could also affect pH drift. If the solution is too weak, pH is likely to rapidly rise as the plants absorb the available nutrients out of the solution. On the flip side, if the solution is too rich, you'll see the pH head towards 0.