NFT is simple in principle, but a few common mistakes can cause problems quickly. Knowing them in advance saves plants.
Pump failure
Without flow, roots dry out. Check the pump regularly and keep a plan for power cuts.
Poor slope
If solution pools in one place, the roots at the low end can drown while the others dry. Level the channels and check the flow.
Blocked channels
Roots and debris can block the channel. Clean the channel and filter the pump intake.
Algae
Light reaching the solution feeds algae. Keep the channels covered and the reservoir opaque.