Maximum Yield Australia/New Zealand January/February 2020 | Page 40

“HYDROGEN PEROXIDE can be used in a hydro system to increase the sanitation level and will not harm the plants.” FLUSHING WITH OR WITHOUT PLANTS If you notice plants in your hydro system are starting to look sickly or show signs of stress, you may be tempted to try and flush your system while your plants are still in it. Your plant leaves may be curling, getting brown spots, or if you accidentally add too much of a particular nutrient or are noticing some algae in your water — but your plants still look otherwise unaffected — it may be time to do an unscheduled flush. This can be done while your plants are still growing in the system if done carefully. Do not try to use any flushing agents not approved for use with plants if you are leaving your plants in place during a flush. The plants will absorb the chemicals and at best will kill them. Worst case, it won’t kill them, but the plants will have absorbed the chemicals and the end consumer will end up eating them. If flushing with plants in your hydro system is the best course of action, there are a couple of options. Hydrogen peroxide can be used in a hydro system to increase the sanitation level and will not harm the plants. Hydrogen peroxide will help the plant by providing additional oxygen to the roots. This is true so long as the amount used is not excessive. Start with food-grade hydrogen peroxide which is usually in a 35 per cent concentration. Dilute this with 10 to 12 parts deionised, RO, or distilled water to reduce the concentration to about three per cent hydrogen peroxide. Add one to two teaspoons (five to 10 millilitres) of the diluted solution per each gallon (four litres) of water in your system. Adding vinegar is another possibility, but this can be tricky if care is not exercised. Vinegar will lower your pH, so keep that in mind, but it won’t harm your plants if diluted enough. Dilute white vinegar down to a similar ratio of the hydrogen peroxide of one to two teaspoons (five to 10 millilitres) per four litres of water. Be prepared to adjust the pH accordingly, though. FLUSHING SALT AND NUTRIENTS FROM SOIL Flushing is sometimes a necessary step in soil culture too. If salts have built up or the plant has received an overdose of nutrients, it can often be saved with a flushing of clean water if caught and acted upon in time. A volume of water at least three times the volume of the container is recommended to try and leach out the unwanted nutrients or other foreign substances. Plants grown in soil culture that do not get flushed when salts build up are prone to root rot or other diseases that will kill the plant or affect the yields. Some growers flush their soil-grown crops as a matter of course during the last couple weeks of the plant’s bloom so that it will be sure to use up all its stored nutrients. 38 Maximum Yield