The plant roots are constantly submerged in water and this can lead to bacterial infections such as pythuim. Pythuim is better known as root rot and can decimate your crops if it is not detected early. There are products on the market that can eradicate this if you are unlucky enough to get it, but the best way is prevention. This can be achieved by changing the water reservoir periodically and adding preventative additives to the nutrient solution.
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