Here is my indoor year round spinach grower. It is a 5 gallon water bottle with the top 1/3 of the bottle cut off, inverted and filled with hydroton. I have it as a
drip system on a timer with a small fountian
pump but you could also use an air pump instead. I still have to cover the nutes to keep the sun from them and the bad stuff from growing, but the plants are loving it so far. I built one like this for fair and it still has the flowers in it. You can see how they are still thriving. I will be pulling them out and putting in some loose leaf green lettuce very soon.
I got this idea off of youtube and of course made a few changes in my style. I have a "how to" on my website if anyone wants an easy project.
I will soon be enjoying some fresh, clean spinach!