Growing fish tank plants

 I have an ongoing problem growing plants for my main fish tank. The tank is a meter deep and i can't just put plants into it i have to drain about 3,000 litres of water and get in. I then decided to get the glass to make 3 tanks where i can keep some fish in them grow plants.

Each tank is 400mm X 400mm X 400mmand i have plants now growing for when i have enough i can then transfer them to my main tank.