How To: Computing the cost of energy usage

Right now I don't have any material for a photo update, but I will later this week as I get the LED lettuce experiment re-started. For now I thought it would be interesting to share how I figure out the cost of energy used to run my bucket farm.

If you are involved in the hydroponics hobby or intend to get involved at some point, you'll need to manage energy usage to manage cost. Depending on your setup and your needs, you will be operating some combination of air pumps, water pumps, fans, lights and perhaps even heating and cooling appliances.

To get started, you need to know how much your energy company charges you for electricity. This is on your power bill and likely on your power company's website as well. This rate is usually expressed as the price per kilowatt hour of electricity used. In my case, this rate is nine cents (.09) per kilowatt hour.

You will also need to know the wattage of the device you are operating. This is easy with lamps, as they usually have the wattage printed on the bulb or base in almost all cases. With pumps, fans, etc, you may have to look at the box or see if the value is stamped on the appliance somewhere.

The formula to figure out how much it costs to operate a device for a certain number of hours is:

COST = ((DEVICE WATTAGE * HOURS USED) / 1000 ) * POWER RATE

Or, to use this formula in a practical experiment, lets say that I want to compute how much it costs me to run a 60 watt light bulb for 24 hours.

COST = ((60 * 24)/1000) * .09


Let's look at this step by step.

1. Multiply the wattage of the bulb by the number of hours it is used. 60 * 24 = 1440. This gives you the watt-hours of electricity used.

2. Divide the watt-hours by 1000 to convert them to kilowatt hours. 1440 / 1000 = 1.44 kWh

3. Multiply kilowatt hours by the price of electricity (9 cents in my case) 1.44 * .09 =0.1296

Thus, it costs me about thirteen cents (.13) to run a 60 watt bulb for 24 hours.

In addition, you can multiply this figure by 30 to figure out the monthly cost: .13 * 30 = $3.90 to operate a 60 watt bulb 24/7 for a month.

You try. Let's look at the cost of operating just my lamp. I use a 400 watt lamp and currently it runs for 13 hours a day because my peppers are now blooming and fruiting. How much does it cost me per day?

P.S. If you leave lights on around your house for other purposes, you should compute how much money you'd save by swapping your 60, 100 and 150 watt incandescent light bulbs out for 13, 26 and 42 watt compact fluorescent bulbs.

How To: Build a supported grow bucket

After losing several nice pepper plants to broken stems, I borrowed the "tomato cage" concept from traditional soil gardening to design a bucket lid which is easy to move from bucket to bucket for reservoir changes and also provides plenty of built-in support for the plant. Here I'll demonstrate how I build mine with parts and tools from Home Depot.

Parts list:

• 1 five-gallon 'Homer' bucket from Home Depot
• 1 'Homer' bucket lid
• 1 roll PVC-coated wire fencing (like this)
• 1 bag 8-inch plastic cable ties (I use these for everything)

Tools list:

• Power drill
• 3-inch hole-saw
• 7/32" drill bit
  
• Bolt cutters or wire snippers

Step 1: Cut the main hole

First we cut the hole that our plant's net pot will rest in.

Attach the hole saw to your drill and flip the bucket lid upside down (it's easier to cut the hole from the underside than from the top, since the lid is slightly recessed). Secure the lid with one hand or a clamp and then cut the hole. The plastic cuts easily so feel free to make the cut slowly and carefully if you have a multi-speed drill.

Step 2: Drill holes for the cable ties

Next we drill the holes that we'll use to tie the cage to the bucket lid. Change the hole saw out for the 7/32" drill bit. Leaving the lid upside down, drill two holes side by side in the inside rim, ensuring that both holes are between (NOT STRADDLING) the little plastic walls that serve as structural supports. Drill three more pairs of holes in the lid so that you end up with one pair of holes each at the north, south, east and west points of the lid.

Step 3: Thread the cable ties

Flip the bucket lid right-side up and pick a pair of holes to start with. Thread the narrow end of a cable-tie into the hole on the right side of the pair. Push the cable tie about halfway through, then flip the lid over. Bend the narrow end of the tie and pass it through the remaining hole in the pair, like so:

Flip the lid back over and pull the narrow end of the tie and adjust it so that the tie is centered through the pair of holes, as such:

Step 5: Cut out the cage

Sorry, I don't have a photo for this step. What you need to do is figure out how much wire fencing you need to cut off of the roll in order to create a cylinder that fits the top of your bucket lid. Unroll a length of fencing and bend it to the shape of your bucket lid until you have figured out how much fencing it takes to make a cylinder. Keep in mind- your cylinder is being secured to the inside rim of the bucket, not the outside. Using your wire cutters, clip this amount of fencing off of the roll. This will be your support cage.

 

Step 6: Secure the cage

Wear eye protection for this step in case you lose your grip on the wire fencing. Bring the two ends of your fencing segment together, causing the cage to take its cylindrical form, and fit it to the topside of your lid. Use one of the threaded cable ties to draw the two loose ends of the cage together and bind them to the bucket lid. You may find this easier if you reach in through the hole we cut in step one.

Work your way around the other three cable ties, tightly securing the base of the cage to the top of the lid. When you are finished, use your clippers to cut off the long portions of the cable ties leaving only the lugs that are holding the cage to the lid:

At this point the cage is secured nicely to the lid and the whole assembly becomes a lot more manageable.

Step 7: Stich the cage shut

 Working your way from the bottom up, use cable ties to stitch the cage closed. Clip off the long ends of all the cable ties, and you are done!

In the next update I'll explain how I use this special bucket to grow plants.

How To: Germinating seeds

Before plants can be grown in the Bucket Farm, they must first be germinated (or started). I'll explain here how I do it. I germinate my seeds in the cheapskate DWC system, which you can read about here.

 Now, let's get started with my overproduced explanation of my germinating process!

Step One: Materials

1) Seeds. In this photo, the incredibly tiny specs at the left side of all items are my Alpine Strawberry seeds.
2) A rooting plug. In this photo I show a Rapid Rooter plug, which are my favorites. [Rapid Rooter]
3) A two-inch net pot.
4) A small drinking glass or clear plastic cup that is at least 2 inches in diameter at the rim.
5) Tweezers or forceps (if you are dealing with small seeds).

Step 2: 'sow' the seeds

Using the forceps or just your fingers, place 2 to 3 seeds into the tiny hole at the top of the rooting plug. You can only keep one plant per plug, but we plant additional seeds to ensure we get at least one plant. If multiple seeds germinate, we'll have to select the strongest-looking seedling and snip the others off.

If you are using large seeds like cucumber or squash seeds, put only one seed into each plug and use multiple plugs to ensure you get more than 1 viable plant.

Step 3: Pot the plug

Plop the rooting plug into the net pot. That's pretty much it. Now take the potted plug and your drinking glass to your cheapskate DWC system.

Step 4: Installation

Insert the net pot with plug into a vacant site in your cheapskate DWC system. Very Important: Ensure that the water level inside the reservoir is high enough that water makes contact with the bottom of the rooting plug. If it doesn't, then add water to bring the level up high enough to touch the bottom of the plug by 1/2 inch or less.

The plug will draw water through its body and to the seeds so you don't need to submerge the plug. Note that in this photo you can see that the water is indeed coming into the net pot and touching the plug.

Step 5: Dome

Place the overturned glass or clear plastic cup over the net pot. This creates a tiny little environment that will get warmer and more humid than the open air, creating better conditions for germination for most plants. This 'dome' should be removed once the plant(s) sprout and have any sort of visible leaf structures.

Perhaps the best improvised dome is the small containers that you get at the nicer taco restaurants to hold salsa for to-go orders. However, I didn't have any of these on-hand so I went with the drinking glass.

Now you just have to wait a week or so (some seeds take even longer!) for your plant to germinate!

How To: Building a cheapskate DWC system

Here's a super-cheap hydroponic DWC (Deep Water Culture) system that I use to grow lettuce and start seedlings of all kinds. Some people call this a 'bubbler' system. In this type of system the plants live in little net pots that are inserted into the top of the system and the roots hang down into nutrient solution. It's a very simple type of arrangement, but very effective.

This system is excellent for germinating seeds and starting new plants, but it's also great for growing simple crops like herbs and smaller varieties of lettuce from start to finish. Another nice thing about this system is that doesn't take up much space- I keep mine on the floor in a closet.

Since it is so cheap and easy to build, I'll briefly describe how to build your own.

First, we'll talk about the materials you'll need:

(Item prices are in U.S. dollars.)

1) One 10 gallon opaque plastic storage tub (Rubbermaid or similar). Ensure that the container is wider than it is tall or you won't get as many plants into the system as you want. This should cost about $7 at a department or discount store. Note that in this photo I have already cut the holes that I need for the 2 inch net pots to rest in.

2) One large airstone. As you can see in the photo I like the flat, round type because they produc a very fine stream of bubbles and tend to stay in one place inside the reservoir. A round one like this costs $8, but you could easily use a 12 inch 'bar' type airstone which you can get at an aquarium or hydroponics store for around $3.

3) One 800-1000 aquarium air pump. This should cost around $7 at a pet/aquarium store.

4) Silicone airline tubing. I prefer silicone type to the regular plastic airline because silicone airline tubing is much more flexible and tends to go where you want it, not where it wants to go. $3 at a pet/aquarium store.

You will also need several 2-inch net pots [shown right] to hold your plants. You can get these online or at a local hydroponics shop and they usually cost less than 25 cents each. All told, you'll probably spend less than $30 on parts.

Now, to assemble the cheapskate DWC system:

1) Place your 10 gallon container into a bathtub, add a very small amount of dish detergent (not soap - use detergent). Fill the container with warm water and leave it to soak. Don't skip this step. You want the container clean of any residues from manufacturing that would otherwise get into your plants' water.

2) Using whichever method you prefer, mark spots on the lid of the container where you will be making the 2 inch holes to hold the net pots. I get 15 well-spaced sites onto the lid of a Rubbermaid 10 gallon container.

3) Using a drill and 2-inch hole saw (or a hobby knife and a lot of patience), cut out 2 inch diameter holes on all spots that you have marked.

4) Dump the soapy water from your 10 gallon container and rinse it VERY well. Leftover detergent would be very bad for your plants.

5) Bring the container and place it where you want the system to live. These containers become very flexible when filled with water and I don't advise trying to move them after they are filled.

6) Cut a length of airline tubing that is long enough to reach from the airstone (which will be resting in the bottom of your container) to the air pump. Connect the airpump and airstone to the airline and plop the airstone down in the bottom-center of your container. Don't start the air pump yet.

7) Add water to the container. The idea here is not to fill the container, but to add enough water that the bottoms of the net pots reach just barely below the surface of the water when the lid is in place. If you prefer, you could put the lid on the container now, place a couple of net pots in some of the holes and add water through one of the empty holes and simply stop adding water when the level of water comes over the inside of the bottoms of the net pots. (NOTE: For the 10 gallon rubbermaid container shown in these photos, this amount works out to be seven gallons of water).

8) Fire up the pump! Your contraption should look something like this:

If you look carefully (or look at the larger version of this photo) you'll see the bubbles bubbling away down in the reservoir. All that's left now is to add your favorite nutrient to the water, pH balance the nutrient solution and add your net pots and plants! I personally use Rapid Rooter plugs to hold my seeds and seedlings in the net pots.

If you have space near a nice sunny window, you could place your DWC system there and not have to worry about providing additional light. I don't have such a window so I provide artificial light using a 125 watt Hydrofarm brand compact fluorescent grow light.