Maintenance

Either way will work. If you are using a nutrient for the first time and are not familiar with how it is going to affect your pH, you should mix your nutrient first. Let the solution sit for about 15 – 20 minutes and then check the pH and adjust accordingly. Keep track of how much pH Up or Down you add to the solution. Typically pH Up will be required if you are using Reverse Osmosis filtered water. If you are using unfiltered municipal water or well water with a pH of 7.5 or above, you might need to use a small amount of pH Down or possibly none at all. Once you know how much pH adjusting solution you use in your reservoir, you can add it first of you like. Remember that temperature affects pH so make sure your water temperature is consistent when mixing your nutrient solution.

pH is a measure of the hydronium ion H3O+. It is based on a logarithmic scale from 0 to 14. “Pure” water has a pH of 7.0. If the pH is less than 7, the solution is acid. If the pH is greater than 7 it is alkaline. Because the scale is logarithmic and not linear, a pH of 6 indicates ten times more H protons than a pH of 7, and a pH of 5 indicates 10 times more protons than a pH of 6.

The ideal pH range for most hydroponic crops is between 5.5 and 6.5.

pH is important because it affects availability and absorption of several of the 16 atomic elements needed for plant growth. Maximum absorption of these elements is found at pH readings 5.5 to 6.5. When pH falls below this range many of the macro elements (N, P, K) have less availability, and absorption of the micro nutrients can reach toxic levels.

pH is adjusted by using an acid to lower it or a base to raise it. General Hydroponics® pH Down and pH Up are designed for this purpose. Many acids and bases are extremely corrosive and dangerous, so care should be used.

When first starting out it is a good idea to measure the pH of your water every day, until you get a feel for your system. Measure your water and then add your nutrients. Within an hour check the pH and adjust accordingly. Repeat this process until pH stabilizes. The liquid nutrient FloraSeries® has special pH buffers to help maintain a desirable pH. It is a good idea to note how much water, nutrients and pH modifiers are needed to obtain the desired values. After several “start- ups” you can generally get a feel for how much acid or base to use for your situation. Frequently pH stays within a desirable range for a considerable time, and then rapidly rises or falls to an extreme. This is usually an indication of the need to do a nutrient change. If you are using hard water, pH has the tendency to climb above 7.5. Sometimes this can be neutralized with acid, though one might consider diluting with filtered water, or adding a reverse osmosis unit in an extreme case.