What is the recommended product and application rate to treat water for pathogen suppression in hydroponic & aquaponic systems? As we've had a number of customers ask questions on this topic and these applications are not covered in much detail in the specimen labels we've decided to cover it in this post.

The recommended product for this application is OxiDate and it can be applied as a direct application to the reservoir at a rate of between 1:1000 and 1:2000 (6.4 fl.oz - 12.8 fl.oz of OxiDate per 100 gallons of water). For any young seedlings a rate of 1:2000 is recommended. For more mature plants a rate of up to 1:1000 can be used. When used in conjunction with a liquid fertilizer the recommended rate is 1:2000.

Since the application of OxiDate at 1:1000 can reduce the pH of water by a few points and root systems vary in their sensitivity to pH changes and phyto-toxicity, we would strongly suggest testing on a small batch of plants using this rate and make sure the plants are ok before applying on a large scale. If any wilting or other phyto-toxicity symptoms are observed, decrease the rate and test again. As a reference, see the attached PDF document that charts PH and ORP values at varying dilution rates.

Once an appropriate rate is determined (1:1000 or 1:2000), apply that rate to the reservoir. If the rate is 1:1000, the solution will have approximately 270 PPM of H202 and if it is 1:2000, it will be around 135 PPM of H202. Monitor the H202 PPM using Peroxide test strips once every 48 hrs and replenish with OxiDate as needed to maintain the appropriate PPM (135 or 270). The dosage calculator helps determine the correct dosage based on the test strip reading.

In aquaponic systems caution should be exercised as we have found that fish cannot sustain sudden pH changes and OxiDate can drop pH depending on the rate and water quality. In this case the manufacturer recommends that a 1:2000 rate is split applied. For example, for 2000 gallons water, at 1:2000, 1 gallon of OxiDate will be applied as 4 applications of 0.25 gallons with a time interval of at least 4-6 hours between each 0.25 gallon application. The pH level should be monitored before and after each application to make sure that pH is not dropping by more than 0.5-1.0 point after every 0.25 gallon application and that at the end of 4-6 hours, the pH of the water is coming back to where it was.

Until the next time - happy growing!