All water will need to be drained from the system . Only pure , preferably distilled , or deionized water should be reintroduced . If these are not available , then at least filtered or reverse-osmosis supplied water should be used . Plants should be carefully monitored during this process and it may need to be done more than once to draw out all the excess nutrients that are stored in the plants ’ systems . There are many commercially available flushing agents that can be used in addition to pure water , but at the very least , pure water must be used . “ Pure ” in this context means neutral as measured by a pH meter having a reading of +/ - 7.0 . Most growers who catch toxic nutrient buildup in time and perform a timely flush will be able to salvage their crops . Within a week , plants should begin to show signs of recovering if they are able to . A modified nutrient regimen can then be reintroduced . Feeding can resume after this period , starting with rates of one-quarter to one-third of the normally prescribed amount . Each week , the amount can be increased so that by the third or fourth week , normal levels of nutrients may be resumed , though of course carefully monitored to prevent toxic buildup again .
Preventing Nutrient Toxicity
Like so many other things in life , the best way to deal with a problem is not to have it in the first place ; nutrient toxicity is no exception . Monitor , monitor , and monitor again . Hydroponic growers should be taking daily readings of pH , EC , and / or PPM . These are simple procedures any grower can competently learn how to do .
Once toxicity is discovered , the hydro system will need to be flushed .”
The challenge of hydroponic growing is nutrient and pH levels can and do change much more rapidly than in conventional or other growing media , so frequent testing is vital . Visual monitoring is essential too . Growers should become familiar with the nuances of their crop ’ s physical characteristics to be able to quickly determine if there is something that ’ s not right .
If there are concerns that any of your hydro crops may be suffering from a nutrient toxicity , do not hesitate to seek advice and act . Bring a picture or sample to your local hydroponic or garden center . Samples can also be submitted to your local cooperative extension office or state laboratories for testing . These tests are routine and costs are relatively low , especially compared to the cost of an entire lost crop . With careful monitoring and following of dosing instructions , most incidences of nutrient toxicity in hydroponic systems can be avoided .