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Using a 27-gallon commander tote from Lowes, I set up a Kratky system with a float valve that will maintain the nutrient level after it has dropped. Maintaining a static nutrient level is ideal with Kratky type systems because overfilling will endanger the aeration roots. I learned about using float valves for this purpose from Matt Garver.
The beauty of this setup is it allows you to use a smaller container and finish growing your plant to harvest without worry of overfilling or running out. You can attach any size reservoir, such as a 5-gallon bucket, a 40-gallon trash can or larger.
It is important to periodically flush the growing container and refill with fresh nutrients. This practice eliminates any excess salts that may have built up, causing pH shifts, leading to nutrient lockout. The easy way to do this is to install a shut-off valve between the growing container and reservoir. When ready to flush, simply turn off the flow from the reservoir. and empty the container. You can lower the float and empty back out through that line, or install a separate drain line. Or have someone hold the plants up and turn the container over.
Another benefit of this system is having the option to change the nutrients easily by changing the reservoir. For instance, moving from a grow formula to a bloom formula.
** This system needs to be partially sheltered if outside, like under a porch cover, awning, etc…. Something that will keep rain out. Additional steps would be necessary to waterproof this for full outdoor exposure. It is possible to do, but not covered in this guide.
- 27-gallon tote – Look for the black tote with yellow lid in Lowes or Home Depot
- Mini Float Valve with 1/2″ barbed adapter
- 1/2″ black vinyl Pond tubing – Look in the pond kit section of Lowes or Home Depot, or order online
- 3/4″ drill bit
- 5/8″ drill bit
- 1/2″ top hat grommet
- 1/2″ barbed connector
- Shutoff valve with 1/2″ barbed connectors
- 5-gallon bucket (or something bigger like a trash can)
- Bucket Lid
- 2 x 6-inch net pots (Two if setting up dual system, else just use one)
- Coco chunks or clay pebbles – supporting medium
- Wrench – for tightening the float valve nut
- Drill – for drilling holes for float valve and the reservoir connector
- Utility knife – For cutting hole/s in the tote lid
- Lid covering – Spray paint for plastic, or aluminum foil. This will block light, preventing algae from growing in the container.
- Drill a 5/8″ hole in the bottom of the reservoir container, clean the hole with a sharp knife.
- Push a 1/2″ top hat grommet through the hole from the outside.
- Push one end of a 1/2″ inch barbed connector into the hole of the top hat grommet from the outside.
- Push a piece of 1/2″ vinyl tubing onto the exposed end of the barbed connector.
Growing container setup
Float valve installation
- Drill a 3/4″ hole (if using the recommended float valve, check the size first) about 1.5 – 2 inches from the bottom and side of one of the corners. Clean this up with the knife.
- Unscrew the locking nut on the float valve and push the threaded part all the way through the container wall from the inside, keeping the rubber washer on the inside touching the container wall. Screw on the locking nut from the outside and tighten with a wrench.
- Adjust the float valve arm to the depth you want to maintain and tighten to lock the position in place.
- Screw on the 1/2″ barbed adapter to the float valve, from the outside.
- Attached 1/2″ vinyl tubing to the barbed connector.
- Connect the reservoir and tote together using a shutoff valve with 1/2″ barbed connectors.
- Optionally install a separate drain line using the same instructions for the reservoir setup, adding a plug or shutoff valve to the end.
- If possible, invert the lid. Some of these style totes allow this, and others don’t. Just turn it upside down and test it. If you can invert it, this will give you a little more headroom. For dual setup, lay two 6-inch net pots upside down and position them evenly, mark the lid with a sharpie.
- Turn the net pot lids right side up and place in the circles, as centered as possible, draw around the base with a sharpie. The hole cut needs to be a little larger than the smallest circles. Draw about a half inch around that circle and this is where you need to cut, as a starting point.
- Use a sharp utility knife, and carefully cut around, make sure not to cut yourself. Test fit the net pots and adjust the hole size if necessary.
- Once the holes are cut, spray the lid with white or black paint, ideally black, then covered over with white. Or you can just cover with aluminum foil.
- Add the water. For the reservoir, fill up as much as you want. For the tote, fill mostly with water. Then put the lid and net pots in place, and finish filling until the water comes up about 1/2 to 1 inch up the bottom of the net pots.
- Mix in the nutrients to the required strength. For Dyna-Gro and Flora Nova series, about 1 tsp/gallon is good. Adjust to around 700 ppm. In the video below, I am using Flora Nova Grow.
- Stir really well, check the nutrient strength and pH. If necessary, make adjustments.
This guide assumes you have small plants already established with roots at least 4+ inches long.
- With the lid and net pots installed, hold the plant in the net pot area with the roots spread and touching the bottom of the net pot.
- Fill in around the plant with supporting media, such as clay pebbles or coco chunks.
- For a couple weeks or so, check the net pots to make sure the nutrient level is still touching the bottom of the net pots until new roots are established and start growing out of the bottom.
The nutrient solution will draw down as the plants and roots grow. Once it gets down to where float valve starts letting in the reservoir solution, this is a good time to flush out the growing container. Turn off the flow from reservoir, empty and flush out the solution in the tote. Turn the reservoir back on and let new solution flow back in. This should be repeated every few weeks after.