Use a liquid pH test kit or pH test strips. Both work without power: you compare a color against a chart. Liquid kits made for hydroponics are usually easier to read in the range that matters for growing.
Liquid Test Kits
Put a small sample of solution in the test tube, add the drops, and compare the color with the chart. Do it in good light. Never test by adding drops to the container itself.
Test Strips
Dip the strip, wait the time on the pack, and compare. Choose strips with a narrow range around slightly acidic values; wide-range strips are hard to read precisely.
What to Aim For
Most hydroponic leafy greens and herbs grow best in slightly acidic solution, commonly cited as around 5.5 to 6.5. Check the guidance for your nutrient product too.
Adjusting
Use pH up or pH down made for hydroponics. Add a little, mix well, wait a few minutes and test again. It’s easy to overshoot, so small steps are better.
When to Test
Test after mixing a new batch, before filling containers. For short Kratky crops that’s often the only test you need.
Related guide: growing Kratky off-grid.
