The problem with pumps
One pump is a good thing. Two pumps are a bad thing.
Twice the chance of failure, twice the maintenance and twice the headaches.
I’ve received a lot of questions about two-pump systems lately- enough so that I decided to do a video response on the differences between one pump and two pump aquaponics systems.
Constant Height Aquaponics Systems
Almost everyone these days does a sump based, one pump system, traditionally called a CHIFT PIST or CHOP system (standing for: Constant Height In Fish Tank, Pump in Sump Tank; Constant Height, One Pump).
There’s a good reason for this. It’s very difficult, expensive or complicated to design 2 pump systems that will operate predictably and safely.
One Pump vs. Two Pump Aquaponics Systems
Most of the time, the reason folks consider 2 pump systems is that they want water flow to be linear, with 100% of the water from the fish tank flowing through the plant production subsystem before returning to the fish tank. It is human nature to want perfect filtration of 100% of the dirty water, and it took me some time to become comfortable with a different strategy. Instead of linear, single loop water flow, I had to become comfortable with fractions in order to reduce the number of pumps in our system to 1.
One Pump Aquaponics Systems for the Win!
So here’s how it works. With a sump tank and a single pump, water is split, with say 50 percent of the water from the sump tank being sent to the fish subsystem, and 50 percent being sent to the plant production subsystem. If my system volume is 1000 gallons and I’m sending 2000 gph through my pump, then at the end of one half hour, around 50% of my dirty water from my fish has been filtered.
At the end of one hour, almost 75% of my water has been filtered. At the end of 1.5 hours, around 87.5% of my water has been filtered, etc.
(Now there is not a perfect efficiency here because waste is constantly entering the water from the fish, but this give you an idea how the system solution can stay clean, even without the plants being perfectly downstream of the fish production.)
Clean and Flexible Aquaponics Systems
By the end of the day, by multiplying fractions by fractions, we end up with almost 100% of our water being filtered through the plant subsystem.
This allows us to keep our system very clean, while using only a single pump. It also gives us more design flexibility down the road, allowing us to size up systems and simply and effectively scale, but that’s a post for another time.
Final Words of Encouragement
If you are in the process of designing your system, I would encourage you to watch the YouTube video associated with this post and design your system with a single pump design. It will save you time, money and frustration as you get your system growing productively and efficiently.