Hydroponics pH Up and Ph Down
Your Hydroponics pH refers to the pH of your system’s nutrient solution. The pH level is critical to your plants ability to up take nutrients and is measured on a scale from 1 to 14. Having a pH of 7 is neutral and is based on pure water. Levels below 7 are considered acidic and levels above 7 are considered basic. How pH is determined at a chemical level is beyond this article and for a deeper article see Wikipedia’s pHarticle.
Your plants ability to up take or accept nutrients through its root system is based on the pH level inside your nutrient tank. Getting the ideal hydroponic pH level becomes a balancing act between what pH level your plant desires and what level best suits each of the macronutrients and micronutrients. For instance having a pH level above 7.0 and iron will begin precipitate out. By 8.0 all the iron will have precipitated out, you will literally see rust (iron oxide) particles, and other micronutrients will soon follow.
The desired pH range varies from plant to plant, however the vast majority of plants will fall somewhere between 5.0 and 7.0. You can find a specific value for most plants on the Internet and most regular gardening books will provide a recommended soil pH. Now the soil pH will not always be perfect as a hydroponic pH level but it will be a good starting point.
Checking Your Hydroponics pH
Bad pH levels only bring dead plants. Testing the pH of your hydroponics nutrient solution is an important process and should be done daily. There are a few different methods to check the pH level of a nutrient solution ranging from cheap to expensive and accurate.
pH Sensitive Paper Strips
The most inexpensive way would be by using the color changing pH sensitive paper. You simply dip this paper strip into your solution. It will change color based on the pH level and this color is compared to the ph color chart provided. It should be mentioned that this is also the least accurate method as the color changes can be rather subtle compared to the change in hydroponics pH level. If you use this method you need to be sure to purchase a paper test setup that is sensitive to a range usable in hydroponics. Again this would be from 5.0 to 7.0.
pH Sensitive Liquid
A slightly more expensive, yet still pretty cheap, method is the liquid pH test. With this method you take a small sample of your hydroponic nutrient solution and add a couple of drops of a pH sensitive liquid dye. The liquid will change color and you compare this color to a ph color chart provided. This method is a bit easier to read and bit more accurate over the paper method. This, along with the paper method, are the two most common methods used by beginners and many hobbyists.
Digital pH Meter
The fastest, most accurate and hassle free method is by use of a pH digital meter. These meters are typically expensive, starting around $40 for handheld meter that measures only pH to around $100 for handheld multi-meter versions that will test pH and concentration. Some of the most expensive version start around $200 and can continuously monitor the hydroponics pH with warning alarms and automatic adjustment.
These digital pH meters also require the most care. The ph meter electrode will need to be cleaned and you will need to go through a ph meter calibration on a regular basis. This requires a special cleaning solution which should be used to clean the sensor probe a minimum of every 4 weeks. Calibration is also done with a special solution and should be done a every few months. Most meters have a replaceable probe that can cost as much as a third of the whole unit. Personally I favor the handheld multi-meters, especially if you have multiple small systems to check.
Adjusting Your Hydroponic pH
Throughout the life of your system and nutrient solution your pH levels will change. This is the result of some nutrient ions combining, your plants using up the nutrients, and a collection of other variables. A stable system will show a continuous increase in pH due to the plants up taking nutrients. So adjusting the pH will need to be done from time to time.
pH Up and pH Down
To adjust your hydroponics pH you can use pH Up (typically potassium hydroxide) to raise the pH or ph Down (typically phosphoric acid) to lower the pH. Both of these can be purchased from hydroponics suppliers and are among the cheaper supplies you will purchase.
Use Small Amounts
These chemicals are pretty strong and usually small amounts will provide a decent change in your pH level. This of course will depend on the size of your nutrient reservoir. When adjusting the pH level add a small amount and let the solution stabilize. Check it every 5 minutes until the value no longer changes. If the level has stabilized and the pH is still off add a little more. Run through these steps until you reach the pH you are looking for. After a while you will get the hang of it and will be able to get the correct hydroponic pH with just a couple additions.