Ebb and flow are also known as flood and drain hydroponics. This system delivers the water, nutrients, and oxygen to the roots of the plants in cycles. The growing area is flooded with the water and nutrient solution and then drained. Flooding occurs and then the growing medium is allowed to dry out before the flooding happens again. This works well because the roots of the plant are forced to grow to search for moisture. The more a plant’s root system grows, the better it can absorb the nutrients and the faster the whole plant will grow.
Ebb and Flow
This system is an intermediate system and quite popular. It is very popular because it is easy to build, does not include any special or expensive parts, and can be made compact for a small space or quite expansive for a large one. This system is also very efficient because the nutrient solution goes through the system several times, and is not just discarded after one journey. This also means that as long as everything is set up properly, the system can run unattended for days or weeks at a time. Just be sure to set everything up for the current stage of the growth cycle the plants are in.
A final advantage of this system is that it can support medium to large-sized plants. Tomatoes, beans, and cucumbers respond quite well to the ebb and flow system. They especially like their roots to be able to dry out when in the flowering and fruit-bearing stages.
Build Ebb and Flow System
There are many different ways to build this system, but they can be purchased ready to go. Go all out and get a table with a tray. This could look sleek and work well. However, a good place to start for beginners is with plastic bins. This system is quite inexpensive, and it will allow the chance to get familiar with all of the components and how it works before upgrading.
Here is a list of the supplies needed:
- Black or dark-coloured storage bin tote, 16-20 gallon size
- 30-quart clear tote (this should be shallow and about the same size as the lid of the dark-coloured tote)
- A mechanical garden timer that can run for 15-minute increments
- Aquarium air pump
- 6 feet of airline tubing and a “T” connector
- 5-inch air stone
- (4) flower pots (8” pots were used in this particular system. Feel free to use smaller pots if that fits your need better)
- Small bag of perlite
- About 18” of ½” inner diameter black irrigation tubing
- Small submersible pond pump (120 gph)
- Fill and drain fitting set with one extension (it is best to order a real kit that is truly meant for an ebb and flow system, and these can be found online)
- Brick of coco coir
- Small bag of LECA (Hydroton or clay balls)
- pH test kit
- Desired number of bottles of nutrient concentrate
- Power drill
- Hole saw
- 3/8” regular or spade drill bit
Ask around to see if any friends have these tools, or buy them. If hydroponics is a sincere passion, these tools will likely come in handy again.
- Cut two 1 ¼” holes in the middle of the clear tote. The holes should be close together, and the pots will need to be placed around these holes.
- Set the clear tray (tote) on top of the lid for the other container. Centre it very carefully. Mark the exact centre of each hole onto the black lid with a marker. Cut two 1 ¼” holes in the black lid right where they will line up with the clear tray set on top.
- Cut two more holes of the same size (1 ¼”) into the black lid. One should go on the far right side in the middle and the other should go in the top left corner. One of these holes is for the pump plug and bubbler tubing to go through, and the other is to peek through to check the fluid level and to add nutrient solution through.
- Grab your two drain fittings and screw them into the centre holes of the clear bin only. Keep in mind that the rubber gasket goes on the underside of the bin. Just tighten them as far as possible with your hand; no need to use tools. Place the extension on the overflow tube (the overflow tube is the thicker one).
- Now, set up the pump. Place the 1/2” irrigation tubing over the water pump outlet fitting. Hopefully, this will be a snug fit; if not it may need to be secured with a zip tie. If it is too tight, hollow out a bit of the tube with a razor knife.
- Put the clear tray that now has the drain fittings attached on top of the black lid. The holes should line up perfectly and the fittings should drop down through the lid.
- Place the pump in the bottom of the black/dark tote, which is the reservoir. The black tubing will need to attach to the port of the shorter drain tube. This tubing will need to stay straight when the lid is on, so it will need to be trimmed. Measure, cut, and try a dry run before calling it good. When the length of the tube is satisfactory, push it over the drain tube and make sure it is secure. If the fit is not snug, use a zip tie to hold it there. The tube mustn’t slip off.
- Place the bubbler stone into the bottom of the black/dark tote, and push the tubing and power cord up through the side access drill that has been drilled earlier.
- Place the lid on top and snap into place.
- Grab a stick or wood dowel to make a “dipstick.” This will allow you to measure how much solution is currently in your reservoir without having to take the lid off. As you fill the reservoir with water and nutrient solution, mark the “dipstick” at every 2-gallon measurement.
- Make sure the setup is sitting on a level surface. Fill the reservoir up with 10 gallons of water. Do not forget the mark the “dipstick” after each increment of 2 gallons. Next, add the nutrient concentrate that you have chosen. If using Flora Grow, Flora Micro, and Flora Bloom (which are very good choices), add 10 teaspoons of each in the order listed.
- Adjust the pH solution with your test kit.
- Plugin the bubbler and pump and test the system. Make sure everything is working as it should and that there are no leaks.
- Now it is time to get the plants in there! Check to make sure the pots fit properly in the bin.
- Drill several ¼” or 3/8” holes around the sides of the pot from the bottom. This will allow for good fill and drainage of the nutrient solution.
- Fill up the pots with your chosen hydroponics medium. A good choice would be to place an inch or two of LECA (Hydroton or clay balls) in the bottom of each pot. This larger substance keeps the medium from flushing out of the drain holes that were just drilled and is just an all-around great sublayer. On top of the sub-layer, fill up the rest of the pot with a 50/50 mixture of coco coir and perlite. This particular mixture holds moisture well and provides aeration.
- Place plants into the pots, and make sure the medium is packed nice and snug around it so it is held in place. Seeds cannot be started in the ebb and flow system because the moisture does not reach the top of the pot. They could never be kept moist enough to germinate. There are a few options for starting plants. Get them going in grow cubes or pellets, or just buy store-bought seedlings and rinse the dirt off of the roots before placing them into the pots.
- Water the plants from the top for the first few days, just to get them used to their new place in the ebb and flow system. Also, be sure to watch the system closely during this period, to make sure everything is working properly. If a little water remains in the bottom of the tray after the drain cycle ends, the pots will need to be raised so that they are not sitting in standing water. If they do sit in standing water, the roots will likely rot, and that is not good. Put something under the pots to raise them about ½”. Something that is plastic usually works well so that it does not add any chemicals to the system.
- Plug the water pump into the timer. Set the system to fill three times a day for only 15 minutes each cycle. Filling at 6 am, noon and 6 pm work pretty well. Plants like to rest during the night, so let them be.
- Leave the bubbler pump with the air stone going all day and all night. This aerates the nutrient solution and keeps it from becoming stagnant.
Keep the system in a sunny window or outside during the day, to give the plants the best light possible. If it is going to be indoors away from windows, a light will be needed.
Maintaining Ebb and Flow System
Be sure to keep the reservoir cool, between 55 and 70 degrees. Also, watch the nutrient and water situation in the reservoir. Water will need to be periodically added. Keep track of how much water is added as levels drop. Once five gallons has been added, stop adding more water. Let the water levels continue to drop, and once the pump begins sucking air, drain the bin completely, mix up a new batch of nutrient solution, and start over again. Every new 10-gallon batch should last about 3-5 weeks if the above mention system of topping off is used. This is a good place to start, but keep in mind that this plan might need to be modified for your exact situation. Also, remember to keep an eye on pH levels.
A few other issues to watch for in the ebb and flow system are algae and pathogens in the open growing container. These issues need to be taken care of right away so that the growing environment does not become unhealthy. The timing of the system may also need some tweaking. Watch the plants and make sure they are happy. If things are not going well, reach out to an experienced hydroponic gardener for help.