Flushing Your iHarvest Reservoir


I am occasionally asked whether it is necessary to “flush” or completely change out the water in the iHarvest®.  Water in the iHarvest® never has to be flushed, however doing so may offer benefits.  For most users, I would suggest doing this very infrequently (perhaps every 6-12 months), unless they notice a change in the growth or taste of their fruits and veggies.

Science Stuff:

The reason you may want to flush the water in your hydroponic garden is because your plants will sometimes uptake more of one nutrient than another.  Over time, this can lead to an imbalance of nutrients in your reservoir, as less utilized nutrients can build up over time.  There are a wide variety of opinions on this matter, but only 1 scientific study that I’ve found.  The study is titled ‘Water and Nutrient Reuse Within Closed Hydroponic Systems.’ It compares lettuce grown in a system where the water is flushed, to lettuce growth in a system where the water is reused.  The study takes place over 2 months and demonstrated that lettuce produced in both systems yielded essentially the same quality and amount of lettuce.  

You may find yourself mixing and matching different nutrient solutions over time, as you grow more than just lettuce and herbs.  This may be a reason to flush your system more often.

How to Flush Your System:

The easiest way to flush your iHarvest is with a siphon pump or submersible  pump.  Simply wait for the water level to get low (but never below the level of your pump), and siphon the rest of the water out.  


Flushing your hydroponic reservoir less often (or not at all) saves money, time, nutrients and water.  It is more sustainable for you financially and it is more sustainable for the planet as it saves water and nutrients.  However, flushing your water every so often may provide tastier fruits and vegetables over time.  I suggest that you begin by flushing your system every 6-12 months.  If you find that it makes a difference to your taste buds, keep doing it.  If you don’t find that it makes a difference, you can flush your system less often or not at all.

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