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Aquaponics Home System – Part 21: Water Test

thomas — Fri, 22 Apr 2011 12:50:04 +0000

The aquaponics fish tank / aquarium is filled with tap water and has been degassing for a couple of days, and it’s time to measure the content of the water:

I’m using a Pondlab 200 water test kit from NT Labs which makes it possible to test 6 different parameters:

Acidity (pH)
General Hardness (GH)
Alkalinity (KH)
Nitrite (NO₂)
Nitrate (NO₃)
Ammonium (NH₄)

The backside of the box shows what you have to do to make each test, along with color scales to find the correct value:

You’ll need to add one or more reagents for each test:

The test kit includes a log for your measurements and a very informative sheet explaining the background for testing each parameter:

(I’m not getting paid to promote this kit I just think it’s cool…)

I used a straw to fill each test tube with water directly from the aquarium and a kitchen timer to tell me when each test was done:

It’s actually easier to get a full cup of aquarium water and then go and sit down at the table instead of bending over the aquarium the whole time, so I’ll do that for the next tests. Some of the tests will take up to 10 minutes before the result is ready.

These are the results from my first measurements of degassed water, but without any fish in the water:

pH: 7.5
Ammonia: 0.1
Nitrite: 0.0
Nitrate: 0.0
KH: 3.5 °DH
GH: 5.0 °DH
Temperature: 23 °C (74 °F)

pH: We’re aiming at a pH value between 6.5 and 6.8 because of the type of fish and plants we selected already, so it seems that there’s a long way down from 7.5, and we’re not sure exactly how to lower this parameter.

Ammonia: This is good. Ammonia is toxic to the fish and must be oxidated into nitrite quickly by nitrosomonas bacteria. 1.0 would be alarming, and 5.0 would be dangerous.

Nitrite: Also good. If there haven’t been any ammonia in the water there won’t be any nitrite because it’s oxidated ammonia. A nitrite spike is expected when fish are added to the water, but the nitrite should soon be oxidated to nitrate by nitrobacter bacteria (or nitrospira?). 1.0 would be alarming, and 4.0 would be dangerous.

Nitrate: Also good. Nitrate is oxidated nitrite and since no nitrite was ever present there won’t be any nitrate in the water. If the level of nitrate goes up and keeps going up it’s because the plant tank is not doing its job of removing the nitrate from the water. The plants need to take up the nitrate through their roots (the N in N-P-K fertilizer).

KH and GH: Don’t ask (yet)

Temperature: A heating element has been dumped into the aquarium and set at 25 °C. It probably needs some time to get the temperature up.

We’re now ready to prepare the floats for the plant tank and add some bacteria.

Garden Webcam Online

thomas — Fri, 22 Oct 2010 11:37:54 +0000

Here’s the picture from my garden webcam. It’s should be updated every minute, but if you don’t see the picture just press CTRL + F5:

Happy stalking!

Configuring Software for My NSLU2 Webcam

thomas — Thu, 21 Oct 2010 11:37:09 +0000

The pictures are coming in from my webcam now and I’m using a program called motion. It’s capable of storing pictures when a movement is detected in front of the webcam, but I have disabled this feature and configured it to take a picture every 60 seconds instead. motion has a small internal web server that can be accessed from the local intranet or from Internet. I’m planning on letting the NSLU2 upload the pictures to happyfarming.com instead, but the local web server is a cool way to test if the camera is running. Here’s a print of my configuration file for motion:

$ cat motion.conf

# The program is run with motion motion.conf &
daemon off

# No debug messages
quiet on

# Path to webcam
videodevice /dev/video0

# Disable motion detection
output_all on

# Seconds between saving a picture
minimum_frame_time 60

# Picture details
width 640
height 480
quality 100

# Picture filename
jpeg_filename webcam

# The pictures are stored here
target_dir /home/thomas/motion/snapshots

# Local web server settings. Replace XXXX with desired port number.
webcam_port XXXX
webcam_localhost off
webcam_quality 50

This is the command I use for running motion:

$ motion motion.conf &
[1] 2147
[0] Processing thread 0 - config file motion.conf
[0] Motion 3.2.9 Started
[0] ffmpeg LIBAVCODEC_BUILD 3355136 LIBAVFORMAT_BUILD 3409664
[0] Thread 1 is from motion.conf
[1] Thread 1 started
[1] Not a V4L2 device?
[1] Using VIDEO_PALETTE_YUV420P palette
[1] Using V4L1
[1] Started stream webcam server in port XXXX
[1] File of type 1 saved to: /home/thomas/motion/snapshots/webcam.jpg

The picture is stored on the USB flash disk connected to the NSLU2.

The previous snapshot is overwritten when this particular configuration file is used, but it’s possible to add a time and date stamp to the filename and make a time lapse series of growing plants. I think it’s even possible for motion to collect the snapshot into a movie file. What a cool program

Now I just need a way to get the picture uploaded to happyfarming.com so you’ll be able to watch me goof around in my garden and throw leeks at the camera

Moving My Garden Webcam

thomas — Wed, 20 Oct 2010 11:37:44 +0000

I had to shorten the USB cable to make my webcam work properly or I would get lots of errors when I tried to grab images. With a shorter cable I had to move the webcam closer to the window and place it on the roof instead:

Here’s the webcam looking down on the garden. The USB cable is going in through the window but it’s still possible to close the window locking the cable into position:

If you look closely you can find the camera on top of the small roof to the left of the house:

There’s not many vegetables left in my garden at this moment although the following plants are still going strong despite the decreasing temperature: Green manure, leeks, parsnips, strawberries and sunflowers.

I tried to get the first picture from the webcam with my NSLU2 computer and installed a recorder program called streamer:

apt-get install streamer

This is the command I used:

$ streamer -c /dev/video0 -b 16 -o webcamfile.jpg

and got this picture:

I have to go work on the brightness setting On my laptop there’s a calibration going on automatically but I guess I have to adjust the settings manually on my NSLU2.

Fixed the Garden Webcam Connection

thomas — Fri, 15 Oct 2010 11:37:39 +0000

My NSLU2 garden webcam setup is working now with the original USB cable on the camera soldered together with an extra 3 m (10 ft) long USB extension cable. Now the link is stable and the data output is consistent:

$ v4l-info 

### video4linux device info [/dev/video0] ###
general info
    VIDIOCGCAP
    name                    : "OV511 USB Camera"
    type                    : 0x201 [CAPTURE,SUBCAPTURE]
    channels                : 1
    audios                  : 0
    maxwidth                : 640
    maxheight               : 480
    minwidth                : 64
    minheight               : 48

channels
    VIDIOCGCHAN(0)
    channel                 : 0
    name                    : "Camera"
    tuners                  : 0
    flags                   : 0x0 []
    type                    : CAMERA
    norm                    : 0

tuner
ioctl VIDIOCGTUNER: Invalid argument

audio
ioctl VIDIOCGAUDIO: Invalid argument

picture
    VIDIOCGPICT
    brightness              : 0
    hue                     : 30464
    colour                  : 40960
    contrast                : 0
    whiteness               : 26880
    depth                   : 12
    palette                 : YUV420

buffer
    VIDIOCGFBUF
    base                    : (nil)
    height                  : 0
    width                   : 0
    depth                   : 0
    bytesperline            : 0

window
    VIDIOCGWIN
    x                       : 0
    y                       : 0
    width                   : 640
    height                  : 480
    chromakey               : 0
    flags                   : 30

But I lost 3 m (10 ft) of length on the cable so I’ll have to move the garden webcam closer to the house to be able to reach the NSLU2.

Debugging My NSLU2 Webcam Setup

thomas — Wed, 13 Oct 2010 11:37:26 +0000

In order to get pictures from my garden webcam onto my NSLU2 computer I installed a program called motion, which is supposed to be able grab pictures from the webcam. I tried several times to get a picture but I got lots of strange errors, so I installed the package v4l-conf to get access to v4l-info. This program is for debugging drivers, but it also produced strange errors. Sometimes the webcam was even gone:

$ v4l-info
open /dev/video0: No such file or directory

Sometimes the webcam would show up but only partial information would be available:

$ v4l-info

### video4linux device info [/dev/video0] ###
general info
    VIDIOCGCAP
	name                    : "OV511 USB Camera"
	type                    : 0x201 [CAPTURE,SUBCAPTURE]
	channels                : 1
	audios                  : 0
	maxwidth                : 640
	maxheight               : 480
	minwidth                : 64
	minheight               : 48

channels
ioctl VIDIOCGCHAN: Input/output error

tuner
ioctl VIDIOCGTUNER: Input/output error

audio
ioctl VIDIOCGAUDIO: Input/output error

picture
ioctl VIDIOCGPICT: Input/output error

buffer
ioctl VIDIOCGFBUF: Input/output error

window
ioctl VIDIOCGWIN: Input/output error

Sometimes the missing information would be available but not the previous information:

$ v4l-info

...

channels
    VIDIOCGCHAN(0)
    channel                 : 0
    name                    : "Camera"
    tuners                  : 0
    flags                   : 0x0 []
    type                    : CAMERA
    norm                    : 0

...

This smells like a hardware fault, and I don’t think I have to look further than my crappy duct tape USB extension cable.

The strange thing is that the USB cable and webcam works on my laptop, although there’s a lot of noise in the picture.

Below is what you can expect, so be warned once I get this thing up and running -

The Tomato Thief Strikes Again :

“But I’m only trying to provide food for my family“, he told the police.

Changing the NSLU2 Webcam Setup

thomas — Tue, 12 Oct 2010 11:37:13 +0000

I have found a way to solve the webcam bandwidth problem on my NSLU2. The physical setup is like this:

USB hub connected to the Disk 1 connector on the NSLU2
The flash memory disk connected to port 1 of the external USB hub. This leaves room for my 1-wire soil moisture sensor in port 2.
Webcam connected to the Disk 2 connector

Now the USB devices look like this:

$ lsusb Bus 003 Device 003: ID 05a9:0511 OmniVision Technologies, Inc. OV511 Webcam Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 004: ID 1307:0165 Transcend Information, Inc. 2GB/4GB Flash Drive Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 0409:005a NEC Corp. HighSpeed Hub

The difference is that the webcam jumped to bus 003 and now there is enough bandwidth for the webcam.

As a side note, bus 002 and 003 are USB 1.1 types and bus 001 is a USB 2.0 type.

Now I just need to find and configure the appropriate software packages to be able to show you some pictures from my garden.

NSLU2 Webcam Test

thomas — Mon, 11 Oct 2010 11:37:01 +0000

I’m testing another way of joining my three USB cables together. The joint is going to be placed outside so it needs some kind of weather protection. I’m considering using ordinary Ethernet cable instead, but I’m not sure what that would do to the USB signal from the webcam to the NSLU2 computer. Using an Ethernet cable I would have a single, long piece of cable instead of three short USB cables joined together.

Five pieces of heat shrink are used as primary cover for the USB wires. One thin blue piece on each of the four USB wires inside the cable, and one larger white piece on the outside:

And on top of that a piece of duct tape:

The connectors from the second and third cable is wrapped in duct tape too:

Hopefully the duct tape will keep the water out.

A preliminary test setup:

I brought my laptop outside to ease calibration of the webcam. The webcam is connected to the laptop through a USB hub:

After the calibration I brought the USB hub back in and placed it in the windowsill behind the NSLU2 computer:

A quick test of the webcam, now connected to the NSLU2, resulted in an error:

$ webcam reading config file: /home/thomas/.webcamrc v4l2: open /dev/video0: No space left on device v4l2: open /dev/video0: No space left on device v4l: open /dev/video0: No space left on device no grabber device available

I did some research and it seems to be related to the fact that the webcam is sharing a USB bus with other devices:
$ lsusb Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 006: ID 05a9:0511 OmniVision Technologies, Inc. OV511 Webcam Bus 001 Device 005: ID 0409:005a NEC Corp. HighSpeed Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 002: ID 1307:0165 Transcend Information, Inc. 2GB/4GB Flash Drive
The webcam needs more bandwidth than it can get with other devices on the same bus.

I just need a way to force the webcam on to another USB bus, or maybe lower the bandwidth requirements of the webcam. I didn’t expect installing a webcam to be that difficult, as I’m pretty sure I had it up and running a couple of years ago.

Mounting a Webcam Outside

thomas — Wed, 06 Oct 2010 11:37:57 +0000

I want to show you what I’m doing in my garden in this very moment, and to be able to do this I’m setting up a webcam connected to my small NSLU2 computer. I have mounted the webcam in a plastic box and then mounted the box on top of a pole with a screw:

As you can tell it’s just a cheap and plain plastic box from the supermarket that I’m using as webcam cabinet:

A cable binder is securing the cable and a piece of masking tape is covering the hole I made in order to get the USB connector out:

Just to be sure that no rain will get in I have covered the hole on the outside with silicone:

And the webcam is ready for live transmission:

The USB cable to the NSLU2 computer was to short so I had to connect two USB extension cables together. I made a simple cover from a plastic bag sealed by two cable binders:

But fast forward a couple of days: My webcam suddenly stopped responding – and now I know why :

The plastic bag with cable binders turned out to be a very poor cover for the USB connectors, and the USB interface probably short circuited

Hopefully the NSLU2 computer is okay – I’ll have to make a better connection to get the camera up and running.

Cabinet for My Garden Webcam

thomas — Fri, 24 Sep 2010 11:59:08 +0000

I have an old Sandberg webcam that I want to use as garden webcam connected to my NSLU2 computer. It’s going to be mounted outdoors but the cabinet I bought is too small to house the webcam when the stand is mounted so I removed it from the camera body:

I’m mounting the camera body on a metal angle:

One side of the metal angle is covered with two pieces of double sided adhesive tape and the camera sticks quite well to the metal angle. I don’t want it to roll around in the cabinet:

Now that the camera is locked into position I just need to make a hole for the USB cable and mount the whole thing outside:

It’s actually a plastic box from the supermarket I’m using as cabinet. I’m sure it will protect the webcam sufficiently to get through the winter, and it’s much cheaper than a professional electronics cabinet.