Backyard Aquaponics
A place to discuss aquaponics

Does anyone know if any of the water readings (PH etc) can be done electronically? If so are there any circuit diaggrams about as my Dad is a bit of a wiz at making these? Just seems would save allot of time.

They can all be done electronically, but I don't think it would save time or money to try and make your own, probes are not so simple.....

I looked into this a while ago.
Circuits are readily available, but the probes are expensive, except perhaps the PH probe.
I would monitor DO and Ammonia given the choice and iirc those probes were 100's of euros each.
And as Joel pointed out DIY probes are not really an option unless you have access to a Uni lab or something similar, then you'd have to calibrate them, lots and lots of work.

Someone (I think gemmel) suggested taking a digital picture automatically of a strip test and running an FFT on it to determine the colour digitally, that would be a relatively cheap and very workable solution imo

I would agree. I do a lot of work with sensors and the company I do work for sells a variety of them, including pH. These sensors are expensive have a membrane cartridge that needs to be replaced and calibrated.

I get the factory rejects for free and I still couldn't be bothered to connect them to my system. I just use a simple fresh water test when I check my systems.

Buy yourself a good quality portable pH meter, IMO it's the only meter you'll need in AP. Amm, N02 and N03 can be easily checked with manual test kits, and once your system is established you'll probably only be doing this this every few weeks, or months, so the kits will last you a while.

A pH meter makes things so easy. With a clean glass I take a 20mm deep sample of the water from my AP systems, sit my pH meter in and walk away and do other checks etc for a couple of minutes, then come back to the meter and have a look at the reading. Leaving the meter for a minute or two like this is important to get an accurate reading.

I've had my Eutech (now Oakton Instruments) waterproof pH meter since 1997 or 1998 and it's still going strong. About two years ago I had to replace the probe, but that's not a bad run I reckon. I've always kept the probe clean, and also moist when not in use for extended periods. I also calibrate it regularly, about every 2-3 months. The Oaktons retail for about $120-$130 these days, the cheap Chinese versions on eBay etc aren't worth a pinch of goat sh!t, they'll set you back about $30 - $40... and there's a good chance you'll be putting it in the bin within a year.

I know people will probably jump all over that last statement with "I've had mine 'X' years and it's still going fine!"... and they are probably telling the truth, but I've bought in two different cheapo brands of pH meters to sell through my shop because some customers don't want to pay for the Oakton meters. With one brand I had a 1-in-5 return rate, the other brand I had a 1-in-2 return rate and only got about halfway through the carton before I threw it in the bin with about ten brand new meters still in it!... I no longer sell el-cheapo meters.

Long story short... a handheld pH meter is probably the only meter you'll need for AP... unless you plan on running a commercial sized system.

Thanks for the answers guys.

+1 for avoiding ebay cheapos. I'm unable to return my worthless $20 PH meter that failed right out of the box.

If you get an electronic you still need to calibrate it with liquids so might as well just use a liquid test kit. I have a nice oakton plus a cheap hanna but find by the time i bother with them and feel sure that the reading is right I would rather just fill a tube and drip some drops. If I had a massive system with multiple tanks I would take the time to calibrate the meter then go from tank to tank rinse recalibrate then put it away cleaned. That is the only way I would trust a meter for ph.

I don't really see calibrating the meter ocassionally as a noteworthy downside, especially for the convenience and accuracy they provide the user.

They don't need to be calibrated each time you use it, as you've suggested. I use mine to check a number of hydro displays and fish tanks probably twice a week and I only calibrate it every 2-3 months. When I do, it's never normally out by more than 0.1... very ocassionally 0.2... that's a poofteenth of f--k all in the scheme of things... and still more accurate than a drip kit and colour chart.

Calibration only takes a couple of minutes every 2-3 months, and the meter basically calibrates itself... you place a small sample of the calibrating solution in a glass, sit the meter in and press two buttons!... I don't see the difficulty, especially when compared to doing dozens of pH tests with a drip kit in that same 2-3 months???

Cheers.

I have to admit... given some recently purchased test kits.... I'm becoming concerned as to their reliabilty...

Both kits were purchased at the same time... but came with widely different colour charts than those in previous kits...

Both colour charts differed considerably... as did the results...

Here's an example... just using one chart, but bottles from the two different kits...... of a pH test... high range test, low range test... and after a pH adjustment...

Yeah have noticed this on the new colour cards as well, and ph7 and 7.2 look identical

BYAP have digital PH meters, I have one and it works great.

Mr Damage,
I was referring to calibrating a "home made" probe interfaced to bespoke electronics.
That would be a lot of work initially in software and hardware development.

If one was prepared to pay the $'s for a commercial probe, then that initial work would be unnecessary.