Flow Rates in Hydroponics Systems
What’s the right flow rate for your application?
As we've discussed in the past, there are many different types of hydroponic growing techniques out there (e.g. NFT, grow beds, etc.). Each of these techniques will differ significantly in the amount of water + nutrient solution you'll need to be circulating throughout the system to grow your plants.
This post will discuss flow rates for hydroponic systems using ZipGrow towers because they are the media-based vertical growing technique we've seen the most production out of here in the northern hemisphere.
Know Your Media, Know Your Flow
First off, it's important to remember that ZipGrow Matrix Media (our specially designed fiber media we've developed over the years) is 93% void space, or 93% air. This means that any water that enters the towers trickles down through the media quickly.
Because of all this void space, the Matrix Media contributes very little to the overall weight of a ZipGrow tower making it very lightweight and easy to move around or transport to market while it's still living. However, because Matrix Media is mostly air, hydroponic and aquaponic growers alike need to ensure their flow rate reflects the rapid rate of percolation the nutrient solution experiences when traveling through the tower.
Having said that, we recommend a constant flow through your towers. Not only is this easier on your pumps in the long run, but it's also an easier way to irrigate your towers at lower continuous rates and give your plants the best chance for optimal growth. (Side note: most pumps are designed for continuous pumping, not so much on and off over and over although some growers do run theirs on timers to save electricity, even if it's not the biggest savings.)
What is the Correct Flow Rate for Hydroponics?
So how much water needs to move through your ZipGrow tower?
In hydroponics, your flow rate can be much lower than in aquaponics- as little as two gallons per hour- because the concentration of nutrients in your hydroponic solution is typically much higher.
Too much flow can cause issues with wet plants. Too little flow could mean not delivering enough water or nutrients to your plants and will likely result in wilted plants or dwarfed production.
We suggest you start with 2 gallons/hour for hydroponics.
Pump Size and Flow Rate are Related
For information about all the variables of sizing a pump, read this blog post.
Since the calculations aren't included there, I've included a simple equation that will give you the volume of water (in gallons per hour, or GPH) that your pump needs to be able to move:
(Number of towers)(2.o)= gallons from towers
The number you end up with is in GPH. Most pumps that you buy will have a GPH number that you need to know.
Note that 2 gallons is the minimum volume of water that you want in your towers, and a bit more wouldn't hurt.
>> Need a pump? We are big fans of this type of submersible pump for hobby/small commercial systems. <<
Flow Rates and the Sustainability of Hydroponics
Now that you know your flow rates in hydroponics systems using ZipGrow towers, the next question is how much water can you anticipate losing each day.
In our system, we only lose 1-1.5% of our total system water each day because we run a very efficient recirculating system.
As you may or may not know, there are traditionally two types of hydroponic systems. One is the "Flow to Waste" system and the other is a "Recirculating" system.