Backyard Aquaponics
A place to discuss aquaponics

Bugger...
Get well soon mate.
Mind you... you don't type with your legs, so pull your finger out and get on with it

ahh damn, what did you do to your leg ?

Haha, I've still been at work with the leg and comming home tired and sore. After 15 weeks of paper pushing digging for nearly 8hrs is hard work.

Had a little graze on my knee that got infected. Put betadine on each night but just wouldn't heal. After i started work, my whole legs from my hip to halfway down my shin was red and swollen. But went to a good doctor who gave me some antibotics and its getting heaps better already...Probably good enough to start coding again...with my fingers of course.

The LCD library is VERY simple to use:
http://www.dfrobot.com/wiki/index.php?title=Arduino_LCD_KeyPad_Shield_(SKU:_DFR0009)
This is the LCD/keypad I got off ebay for under 10$

Theres some sample code below to have a look at. The problem is the SD and LCD both want to use the same digital pin 4. It shouldn't be too hard to figure out a fix but I've been to slack to put the effort into breadboarding something up.

I realize you're going the way of probes in the water, but for anyone else, SuperVeg posted this link to what looks like an all plastic, submersible float switch. It could be an easy solution for anyone wanting one.

http://www.altronics.com.au/index.asp?a ... &id=S1160A

Thanks BullwinkleII, I was going to post it here also, then I got distracted by something shiny...

I solved my sensor problem, nothing to do with noise at all, but a _very_ strange software problem.
Turns out that switching the drive to the sensor(s) OFF was causing the next read of the sensor to occasionally read a false positive.
I just inverted the logic in the s/w and it has been faultless for a month.
One just has to accept these little s/w idiosyncrasies from time to time

heh indeed

This is something i have been looking at to add to a datalogger. It is a fairly pricey, but it would be interesting to log as well. It is a shame that i havnt been able to find anything similar for nitrites and nitrates.

I have been wanting to take a look at arduino. I have some experience with picaxe and the propeller. It is just a matter of being able to afford a new dev set

They exist, but are prohibitively expensive for a backyard system.
200 USD per probe, somewhere around there.

I have seen a few, but they all look they connect to a PC that requires proprietary software to read. Not really suitable for electronics integration.

They generally give a millivolt reading, highly suitable to electronics integration

indeed
However the output may not be linear, and you may have to come up with some sort of quadratic equation to calibrate the probes. A lot of mucking around if it is not a linear response. But if it IS linear.. YAY !

I think those probes(or just the tips) also need replacing kinda often, and calibrating with known samples.
Bioslime may also block the probes and force more regular replacement.
You might need some system to only expose the probes to the water when you want to run the test.
This is all very doable and would be a fun project. I just don't think it would be a cheap project unfortunately

I think you need to clean the probes before each reading.

I left a millimetre in my water for a few days to see if I could read any changes in anything (just measuring resistance, and comparing it to my test kits reading to see if there was any correlation - I think salinity was all that I could detect), and after only an hour or two I started to get false readings. I'm guessing from oxidation or slime or something. The probe has to be reactive in some way.

After cleaning, readings went back to the original readings.

I wonder if there's a way to do something with light, and prisms. Not really sure what it would read, but you might be able to detect water colour or more with PICAXE's colour detector, or even a web cam.

You would still need to take a sample with a clean probe. or pull a drop out or something.

One way to sample might be to dip a new probe in each time. ie a spoked wheel or something that stuck a probe in every hour or something. Or even the same probe, but lifted out of the water and dipped into ammonia or something between readings. Easy enough to do reliably with PICAXE stuff, so I'm sure it would also be with Arduino.

snap

Any chance of a link? The ones i had seen im my quick google a few days ago were only really for industrial type applications and look expensive or direct pc connection.

I wonder, if you had to take the probe out, you could just attach it to a board and use a small stepper motor to raise and lower it. Assuming you had a constant water level of course