pH measures how acidic or basic a solution. Acidity means a pH below 7 which is Neutral. The pH scale runs from 1 to 14. pH by definition is a logarithmic measurement of the hydrogen/Ion concentration of a solution. Most hydroponic systems will require a pH around 6.0 to 7.5., a good range for herbs and greens.
Why is this range from 6.0 to 7.5 necessary? Due to availability of nutrients in your solution, this will vary pH. If you go to high or too low you might see deficiencies in your plants. If you keep your pH at a happy medium your plants will be happy. A bit of pH flux can be good, it gives plants a variance of what’s available, Various crops have different nutrient and pH requirements, some require very high pH, most tend to be acidic.
How you manage pH?
You need a handheld pH meter, to read nutrient concentration, monitor the pH daily, as it fluctuates. One can use auto dosing systems hooked-up to your reservoir and dose for you from a reservoir tank of pH down. There is also litmus tests, a strip of paper indicating the level when dipped in solution.
If you have a handheld meter you need to calibrate it, you need a calibration solution, which is available in 7.0, watch expiration dates. You need an 4.0 solution to calibrate your meter. Most meters have instructions on how to do the calibration. It is recommend to get probe cleaning gel solution as a dirty probe will not read correctly. A little goes a long way. Do research online when purchasing a pH meter, don’t buy the cheapest thing available. Get a reputable brand, this is the best investment you can make if growing plants.
Adjusting pH
Once you can monitor your pH you can take steps to adjust your PH. Starting at what pH your tap water is when coming out the tap? If your PH is neutral you use pH down. It will vary with seasons so check your tap water regularly. If your water is acidic you will need to use pH up. There are various methods to lower pH other than store bought solution of pH up & down. If you have an acidic water source you may want to try sodium bicarbonate, lemon juice, vinegar or lye (which are all high pH), not advisable! This is harmful for plants and microbial life and can change the electrical conductivity of your solution. You may lose your plants, one uses small amounts of the solution pH up & down, it will last months.
Dosing
pH can be difficult to adjust. All is dependant on the size of your reservoir system. Check your pH, everyday, if you are doing it manually, adjust it manually, it will change frequently. Be careful of getting your solution acidic, you could get acidophilic bacteria growing in your reservoir which is bad. You need check everyday to keep your levels acceptable. When adding nutrient solutions, it is acidic, so lower your pH, going for 6.0 – 6.5 range. Plants have selective ion uptake.
If you have a high carbonate content in your water, hard water, it’s common. It buffers the pH and makes it difficult to adjust and even adding your solutions won’t change it much. You can have your water tested to find out the carbonate content. If this is so, you need a special RO filter system to filter this water before putting it in.
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