DIY Hydroponic Flow Through System

• Over the past three years, our greenhouse sales have grown by 3.22x. That’s not a typo. It’s the result of:

  • God’s blessings

  • Getting our nutrients dialed in

  • Keeping our oxygen levels consistently above 18mg/L with our AirCone system

  • Growing more herbs

  • And—what I want to talk about today—a simple, low-cost, but powerful upgrade: the flow-through system.

This system cost us less than $100 to implement, and it’s one of the most important changes we’ve ever made. The concept is incredibly simple: inject fresh water constantly, and let a little water flow out at all times. It keeps toxins from building up, your nutrients fresh, and your plants exploding with growth.

We use cheap Rainbird pressure-compensating drip emitters to inject a known flow rate of water—about one gallon of fresh water per 12 to 18 square feet of growing area per day. For the overflow, we run standard black poly hose that carries the used water out of the greenhouse to a gravel pit.

About two years ago when we implemented this change, the lettuce in the front of our greenhouse was ready to harvest, but the lettuce behind it had grown so fast we threw out the first several rows of rafts. That’s how powerful this growth boost is.

You lose a little bit of nutrient with the overflow, yes—but you gain so much more in plant health, consistency, and speed. In our opinion, there’s something simply magical about fresh water. Add to that the fact that you’re avoiding salt and sulfate buildup, and your system stays clean and high-performing.

A greenhouse that isn't producing at its full potential is not as sustainable as one that is. You're still heating it, cooling it, maintaining it—but you're not getting the return you should be. Flow-through helps unlock that full potential.

If you are having issues with your crop, the first thing the big companies like Crop King and AmHydro will tell you is to dump your water and start over. I know Crop King says to do that every two weeks. That does work—but it doesn’t work as well as the flow-through system. It just doesn’t. I’m honestly shocked that these big companies haven’t caught on yet.

Run your own tests. Within about two weeks, you’ll see the difference.