Two-Bucket System

Deep Water Culture Two-Bucket System

Excerpted from “Small Spaces, Big Yields” and featured in High Times March 2014.

Building DWC buckets that don’t suck—this is my time-tested and hard-earned contribution to the hydroponic pot-growing community. My DWC system—a system that is simple, cheap, elegant, low maintenance and that really moves plants along, if I do say so myself.

Equipment List

  • 2 x 5 gallon black bucket.
  • 1 x bucket lid.
  • 2 x 1-1/2” Uniseal® – pipe to tank seal.
  • 1 x 18” piece of 1-1/2” diameter black PVC pipe.
  • 1 x 2-3/8” hole saw1 (multi-toothed, not the wood saw variety).
  • 1 x 6” bucket lid style mesh pot.
  • 1 x heavy duty air stone.
  • 1 x two or four hose air pump.
  • Standard blue air tubing.
  • 1 4” x 4” rock wool cube, drilled. I prefer Cultilene® cubes because they do not require pHing before use. You are only dealing with one or two plants so buy your plants started in rock wool.
  • 1 x PPM pen (cheap, with temperature compensation).
  • 1 x pH pen (cheap, with temperature compensation).
  • Nutrients.

Gather the items identified in the list and do not substitute. You need Uniseals®. You need a multi-toothed hole saw, not one that will tear and rip at your bucket. You need black buckets, not orange or white. You need a lid and you need black PVC pipe. You will also need a hacksaw to cut the PVC pipe into an 18” piece, a power drill, a wood file (bastard), and some soap and water. You’re also going to need some muscle. Sorry, no way around that, but I promise it’s worth the effort. Got your stuff?

This is how the hole should be positioned in the bucket.

Measure up from the bottom of the black bucket 2.25”, positioning the guide bit on your hole saw in line with the axis of the bucket handle. Now drill your hole. Try to maintain control of your drill. you want the hole saw to cut, not tear.

Now clean the plastic flashing from around the hole.

And pop in your Uniseal®.

View of the Uniseal® from the inside, note how the plastic debris has been cleaned away.

This sloppy job will probably leak.

Cut a piece of black PVC to 18”. You will have a sharp edge on the PVC.

Very important: sand or file those edges round or they will bite into the Uniseal® and you’ll never get the PVC pipe through the Uniseal®.

Put some dish soap and water on the PVC and inside the Uniseal® to make the insertion easier.

Now, insert the PVC into your second bucket so that the finished product looks like this.

Two buckets properly conjoined.

Insert blue tubing through the net pot like this.

Why two buckets for one plant?

Your plants are going to get big and heavy and they are going to be pushing against your SCROG screen, creating yet more downward pressure.

You don’t want to have to be lifting the net pot off to the side every time you need to add nutrient or water. The root ball is also going to fill the bucket and displace most of the water in it. With the two bucket system, you just lift the lid of the nonplant bucket and make your additions and adjustments there.

The additional reservoir will also ensure that you can leave for a few days without harming the plants. I have found that it is possible to leave for up to 7 days in full bloom and expect healthy, happy plants when you return. (If you do this, remember that your ppm is going to increase over that time as the plant takes up water faster than food, so you should start with around 800 ppm if you want to come back to 1200 ppm, otherwise you could end up with some leaf burn.)

Now it’s time to put your plants in and watch them grow. Simply remove the plastic wrap from around your cube, drop your plant into the net pot and fill in the gaps with loose rock wool. The objective here is not to pack the roots in, but just to close the gap around the top with enough rock wool to block light that would otherwise fall on the roots. Roots exposed to light will develop chloroplasts, which is a waste of plant energy and a waste of good root area. Then you fill your DWC bucket system up with nutrient to just below the net pot. You don’t want the net pot in the nutrient, you want it just above the nutrient. Make a mark on the lidded bucket at this level to make future refilling easier. Thread the blue hose through the net pot and out the top so you can get a good seal between the net pot and the bucket. Put your airstone on the end of the blue tubing. The air stone should rest on the bottom of the bucket (see photos). Now when you send air through the air stone and the tiny bubbles pop at the surface little droplets of nutrient will land on the root ball. In a few days the roots will begin to grow down into the nutrient. Soon the root ball will become impressively voluminous.

When adding nutrient, because the two buckets are connected only by a small pipe, you will need to be careful with ppm measurements. The two buckets will balance but it will take several hours for the concentration gradient to equalize (I let it equalize overnight before taking my final reading). You are always averaging what you add with what is there and there are two variables, concentration and volume. I add 1000-1100 ppm once they are up and running (having increased concentration incrementally over a period of 3-4 days) and then I keep an eye on ppm changes. Recall that the plant will use water faster than nutrient, so there will be times when you want to only add water. I find that I never have to exceed 1200 ppm.

A clone ready to transplant to your DWC system.

Close up the gaps around the rock wool cube.

Roots beginning to grow into the nutrient broth.

The root ball will fill most of the volume of the first bucket.

DEEP WATER CULTURE BUCKET SYSTEM – SUMMARY

Take your time to build this inexpensive, leak-proof, high-capacity, two-bucket deep water culture system. You will be rewarded with a system that is easy to use and will support the healthy growth of your plants for many days without your input or attention.

  1. NOTE: This was incorrectly identified as a 1-3/8" hole saw in the March 2014 High Times and in earlier versions of the book, Small Spaces, Big Yields. It has been corrected as of 1/22/14. The author apologizes for the error. (The reason for the slightly smaller hole than Uniseal® is to provide adequate compression and prevent leaks.)

    Also, in HT the final paragraph was editorialized. I do not prefer 450 W HPS; I like 600-1000 W HPS.

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