We recommend to use flat cultivation rather than A frame for NFT lettuce hydroponic in greenhouse. There are several reasons why more people choose flat cultivation:
1. The number (yield) of planting slots is actually similar. For example, for one span, you can put 48 cultivation pipes with A frame, 45 cultivation pipes with flat cultivation. Not much difference in quantity. But the price for A frame is much more expensive than flat cultivation.
2. The yield of flat cultivation is relatively stable, and the influence of light is relatively small. But for the A frame, If there is not enough light in the area, the lettuce on the lower level will not get enough light and will not grow well.
3. More convenient installation and lower transportation cost for NFT lettuce flat cultivation.

4. It is more convenient for growing and harvest with flat cultivation in the greenhouse.