The Glass Greenhouse – 2004 Season

As we are currently in the process of moving house, This Greenhouse is the only one which I have to grow within this year. I have started trying all sorts of new ideas out though, And you’ll find more information about these as you read more of this page.

As you can see in the picture here we are still growing lettuces in a cold frame outside the greenhouses like we did last year. (Please see last years greenhouse post  for more details on how this system works)

This year though I had to purchase a new air pump for the system as the belows inside the old pump had split during the winter. I also purchased two new ready perforated plastic pipes to use to supply the air to the nutrients. I am also running the air pump 24 hours a day to see what effect this has.

The system with it’s new pieces and adjustments is now performing much better than last year, To see an example of this have a look at our photo’s from this season by clicking Here.

Although this photo doesn’t show it we have also wrapped parts of the Greenhouse in large bubblewrap. This is because the cucumber plants were getting burnt from the sun.

As I didn’t have much space to play with this year having only one Greenhouse I decided to try and grow the watercress outside this year.

As there is no electricity elsewhere in the garded I decided to try and use solar power, I purchased a Solar Fountain kit from a local DIY center, The kit came with a low power water pump and the solar panel you can see here.

Unfortunately due to the lack of sun in the UK the pump doesn’t run for 95% of the time which doesn’t make it much use, To fix this I decided to built a little piece of electronics consisting of a few capacitors and a timer circuit, What this basically does it charge the capacitors up using the limited solar power available and every 20 seconds pulses the pump for approximately 2 seconds. This is enough power to pump a small amount of nutrient solution up to the Watercress channel shown below.

Shown here is the Solar powered NFT watercress system, The system is made up of a nutrient container (The green box) , This contains all the nutrient solution.

The nutrient is pumped every 20 seconds for 2 seconds by the solar panel, The solution is pumped up into a piece of standard square guttering where it flows down into another piece of guttering underneath and back into the nutrient container to start the process again.

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Automation and Monitoring the Greenhouses

This year (2004) I have started having a little play at making a monitoring system within the greenhouse, I was originally planning on using X10 equipment to automate the greenhouse. Due to the expensive nature of this equipment in the UK though I have decided to use a different method to monitor and automate the greenhouse.

dallas1While browsing the web I stumbled upon some electronic products from Dallas and Maxim called 1-Wire and iButton.

I then decided to purchase a development kit to use for this purpose.

This equipment allows you to connect sensors and switches etc. to a computer for reading and also to turn things on and off, This is all done with two wires which means the only thing I needed to connect from my house computer to the greenhouse was a small cable with two cores.

This system appears to be used quite extensively by home users who have weather stations set up, which makes it ideal for my kind of measuring and monitoring setup.

smallpc (1)I had already purchased a computer for use in the house which was to be left on all the time so I had a computer ready to use.

This computer I had was a VIA EPIA 5000 Fanless Motherboard in a tiny case, This combination only uses approximately 10 watts of electricity, Compared with 250 watts like a normal PC.

It’s also completely silent as there it’s passively cooled and there are no fans used in the computer.

The computer is connected to all the 1 wire products by a simple adaptor plugged into the serial port, This adaptor came with the development kit I purchased.

I decided that to start with I needed to be able monitor the temperature within the greenhouse (And later outside the greenhouse), Check for nutrient levels being low in the tank and also to be able to switch off and on both a heater and a fan, The products below are are the ones I chose for this purpose, All are low cost items.

1 Wire items used in the Greenhouse

DS 1820 – 1 Wire Thermometer
DS 2401 – Silicon Serial Number (Switch)
DS2405 – Addressable Switch (Fan)

floatswitchTo connect the temperature chip is simply a matter of connecting the two wire cores from the house to the legs of the chip.

To connect the low nutrient level sensor (Home made off course as you can see in the picture here.) was simply a matter of connecting the serial number chip DS2401 to the same two cores but through a microswitch. The microswitch is connected via a piece of string to a floating piece of lego which pulls the microswitch on when it starts floating to low.

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