Ebb & Flow System

Mainely Hydro returns with the fourth installment of our blog series, this time featuring ebb and flow systems. There are a few variations of ebb and flow systems utilized for hydroponic gardening. This blog will focus on an ebb and flow system that requires a grow table. Ebb and flow hydroponic systems work just like their name suggests. With the use of a reservoir, water pump, and timer, nutrient water ebbs and flows periodically into the grow table. This allows plants to uptake the nutrient water when available, while still enjoying oxygen to the roots when the water flows out. If maintained properly, ebb and flow systems can nurture both large and small plants, making them useful throughout hydroponic horticulture.


Grow table, grow medium, nutrient water solution, reservoir, water pump, air pump, air stone, plastic tubing, ebb/flow fitting, overflow tube , and timer.

ebbflowThe ebb and flow design is one simple enough for personal use, yet still sufficient for commercial use. As mentioned above we will focus on an ebb and flow system with a grow table. Other variations of an ebb and flow system may be more beneficial to later stages of plant growth, or for larger plants in general. The grow table is where your potted soil or soil-less plants will sit. Drainage at the bottom of the plants will be necessary, so be sure your pots have holes at the bottom. A grow medium like rockwool could also be used. Rockwool can be placed directly onto the grow table without additional potting.

When choosing a grow table, keep in mind it will have to be deep enough to hold a few inches of water. The addition of a simple overflow tube will ensure the grow table doesn’t overflow. The top of the overflow tube should be a few inches below the top of the growing medium and run down to the reservoir. A hole will have to be cut into the reservoir top to include entry for the overflow tube.

Another major component of this system is the ebb & flow fitting, which acts as the entry point for water into the grow table. If your grow table doesn’t have an ebb/flow hole, cut an additional hole to accommodate the fitting into the bottom of the grow table. Place the fitting into the hole, then proceed to cut out a matching hole into the top of your reservoir. Plastic tubing can then be placed onto the bottom of the fitting, which runs down into the corresponding reservoir hole to attach to your water pump. Some research will be necessary when choosing the right water pump. The pump will need to be strong enough to pump water up the tubing, but not so strong that it will shoot water out of the table. After connecting the fitting and water pump, the system will need one more crucial device to control its ebb and flow cycles.

The use of a simple timer will be necessary to trigger the ebb and flow cycles. Determining your system’s cycles will depend on the size of your plants, quantity of plants, and the growing medium you decide to choose. Some systems may need one watering a day, while others may need to be watered three to four times a day. Be sure to initially flood your table with the plants on top, observing how long it takes to fill to the desired level, as well as how long it takes to drain. Then, set your timer accordingly to your observations. It may take a few days of trial and error to figure out the correct timing and duration for your system’s flow cycle.

Ebb and flow systems also use a reservoir just like the previous three hydroponic systems we’ve introduced. Mainely Hydro highly recommends using an air stone and air pump to reintroduce dissolved oxygen into your nutrient water solution. Since ebb and flow systems recycle their nutrient water supply you will have to periodically check its ppm level for nutrients, as well as its pH level. Your reservoir may need to be changed completely during the grow process if water becomes dirty or algae ridden. Due to fewer watering cycles needed, and reusing the nutrient water supply, ebb and flow systems can be much more cost efficient than other hydroponic systems. Larger plants, like flowering cannabis plants, may outgrow the design of a tabletop ebb and flow system, especially with numerous plants sharing the same table. Other variations like a bucket ebb and flow system may be better suited for larger setups. In this kind of ebb and flow setup each plant has its own grow table, or in most cases bucket, which connect to each other with tubing. Water ebbs and flows out of each container with the assistance of a timer, similar to a tabletop ebb and flow system. In addition, the open grow space of a tabletop ebb and flow system encourages plants’ roots to sprawl out, usually intertwining between one another. If you plan on re-potting in the future, this may not be an option with intertwined roots.

Overall ebb and flow systems are efficient hydroponic systems. Their efficiency relies on reusing the nutrient water supply, as well as using less energy with limited water pump use. Grow table ebb and flow systems can be great setups during early plant growth, and often are utilized for propagation purposes. However you may discover as your cannabis plants grow, they require more space than the tabletop can provide. To allow your plants to continue to flourish, simply transfer them to a larger grow space. This should be an easy task as long as your plants’ roots haven’t completely become intertwined.

Only two hydroponic systems left to introduce in this series! Next week we push forward to familiarize beginners and green thumbs alike with aeroponics. 

Posted on: April 14, 2016, by :