Proper pH control is an essential aspect of any successful hydroponic system, from small, home-built systems to professional systems used by commercial hydroponic agriculturalists. If the water supplies, nutrient solutions and and growing media you use in your system are not all kept at the right pH, plant growth will be slowed and stunted, and you may fail to get a significant crop at all. 

Fortunately, properly controlling the pH of a hydroponics system is not overly complex, but there are a few essential supplies you will need to make the job easier and keep your plants safe. The following key supplies can all be obtained from any good hydroponics shop or wholesale supplier:

pH testing supplies

The pH level of a hydroponic growing solution isn't exactly something you can eyeball, and you'll need some means of measuring your system's pH levels that can be used safely and frequently. 

Home growers and hobbyists can usually get away with using simple paper strip tests — essentially a more complicated form of litmus paper, these testing strips can give you an instant pH reading, though not a very accurate one (forget about decimal points).

Liquid testing solutions work in a similar way and are used to colour a small sample of your hydroponic solution to indicate its pH. These are slightly more accurate than strip tests, but using them accurately is heavily dependent on proper lighting so you can properly see the solution's colour — inconvenient if you are growing mushrooms, forced rhubarb, or other plants or fungi that benefit from darkness.

Electronic pH testers are considerably more expensive than strips or liquid, but they are a one-time purchase that is generally best for the serious hydroponicist. They can provide extremely accurate pH readings in a matter of seconds, although they must be re-calibrated frequently to stay accurate. 

pH adjusting solutions

Knowing the pH levels present in your hydroponic system is all well and good, but you'll also need a way to adjust it if it's out of balance. PH adjusting solutions, usually marketed as 'pH up' and 'pH down' solutions depending on their function, are the easiest and most widely used way to adjust the pH of your growing solution and medium.

These liquids often come packaged with testing kits, although more dedicated growers will probably want to buy top-of-the-line adjusting solutions separately. The key to using these solutions effectively is to give them time to work their magic — you will usually need to wait up to half an hour after using an adjusting solution before you can test the pH again.

pH-neutral growing media

The solid medium you use to give your hydroponic plants stability and strength should be completely pH-neutral, and any acidic of alkaline compounds present in your chosen medium can cause pH levels to rise and fall dramatically.

Most media types stocked by hydroponic shops and suppliers are pH-neutral, but there are a couple of pitfalls to avoid. Rice hulls, a popular medium, are usually slightly acidic — this acidity is actually within the ideal growing range for most plants, but some plants with more obscure needs may be damaged. You should also be careful if you choose rockwool as your medium, as it is somewhat alkaline and needs to be soaked in pH-neutral water before it can be used safely.