Lets talk about pH testing.

budbro18 said:

Anyone look into making a ph meter out of an arduino?

Ive seen people make fully automated systems with them for relatively cheap.

check out this one: http://arduinogrc.blogspot.com/2011/09/here-is-my-arduino-based-grow-room.html

Ive seen alot prettier versions of them but these are all i can find right now. The one i saw once had controlls to automatically adjust ph with ph buffers, ran fans and a/c at certain temps, and added nutes at certain ppm.

Click to expand...

I've seen automated instruments used in the field. They still require the grower to add the buffers and push the cal sequencing button. The function would still be the same, yes? The instrument reads each buffer and does an internal adjustment on each, then provide a slope. This is the same principle as when a screwdriver is used to manually adjust the set-point.
Or are you saying that it then adds chemical to the hydro system that also adjusts the pH in the reservoir?
Might be a cost effective option for a large grow operation.

Yeah theyre really simple computer chips that only run at 100-200 mhz and sometimes less. They are made for prototyping so they accept basically anything that can be controller (not really but you know what i mean)

So you get a connector for all the probes like the ph, tds, temp (both water and air), hygrometer, fans/ac, and even co2. Connect the probes to the mini computer then right the code for everything or select a premaid code (which they have a tone of)

Then you just get connectors running off the main pc board to small computer controlled pumps. stick one end of each tub running off the pumps into nutes, ph soluution, plain water res, and youre good to go. While having electrical controllers running off the main board to fans, or a/c or whatever you want. You can even connect your ballasts to them.

Calibrate at first run and you should be good for a few months. You could even right code to auto calibrate when you fed them regular water so when it phd to 7.0 itll calibrate.


this is probably very similar to how the guys who make those ALL IN ONE self sustaining grow boxes that are a few thousand dollars made there products.(the oness in high times)

At least there prototypes of it haha. Really cool technology we have access to now a days.

You could leave that grow for weeks on its own if you configured it the right way.

Great vacation strategy!

You should post a tutorial in the DIY section if you ever decide to build one. Dudes on here love that kind of stuff.
And where to buy the parts and access the codes. Sounds cool.

For the super-geeks:

Here is some methodology that is approved for water and wastewater testing of pH

A link to the approved EPA method 150.1 in EPA publication 600/4-79/020, March 1983, 550 pages:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&sqi=2&ved=0CFwQFjAG&url=http://www.in.gov/dnr/fishwild/files/Methods_Analysis_Water_Wastes_USEPA_March1983.pdf&ei=3RsAUpXzBOn6iwK49oGgAg&usg=AFQjCNHRVtRJ3G4uP553ypCE0znuhVBGGw&sig2=y1f3Gn0B_Nw-axaOEJU5sw

Hach Company:

http://www.hach.com/asset-get.download-en.jsa?code=56935

NEMI:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&sqi=2&ved=0CGMQFjAH&url=https://www.nemi.gov/methods/method_summary/4685/&ei=3RsAUpXzBOn6iwK49oGgAg&usg=AFQjCNGbSND_6a6STl1EVNsFpWvmm9Hg_A&sig2=HIxubsWYLkDokMm8WjToYQ

Wish I could put up pages from Standard Methods, but they wont allow that.

aisach said:

Great vacation strategy!

You should post a tutorial in the DIY section if you ever decide to build one. Dudes on here love that kind of stuff.
And where to buy the parts and access the codes. Sounds cool.

Click to expand...

For sure! im more of a soilless grower so i dont have a res or anything like that. But if i ever go to a self irrigation system i will for sure. ill try postin some links or youtube videos of diys.

Essentially you could plant the seeds and leave it until its ready to harvest but i wouldnt recommend it for obvious reasons.

One of the reasons that growers don't take pH seriously is because there is a lack of information conveyed to them.

A local hydro shop in my town has 5 locations in the state. I talked to the owner about teaching his staff as well as clients about basic lab work necessary for garden environments. He was interested, but perhaps not enough to act. If the stores took more interest in their customers having 'great' gardens, more growers would have 'great' gardens. There is more to it then choosing the right strains, and equipment. I see several reasons for this.

1. There is a lack of space to showcase the items and techniques, and translate those into sales.
2. The profit-margin may, or may not, be there.
3. Staff doesn't understand the methodology, technique, or necessary supplies to make the sale. They can, however, tell you what the temp, pH, and solids should be.

I offered to help FOR FREE. Just like here on RIU. And I plan to try again, after they have the local store fronts re-vamped.
Mind you this is for those clients that actually care, and see the benefit of it. The whole issue is lost on noobs (who would be future customers) because all they see are a few pens thrown in the display case, with a shot glass.

The industry is moving toward a white collar professionalism, and I hope that the stores can make the step up too.

So this is what the equipment and supplies look like.
Anyone can set this up for not a lot of money, although these examples show a laboratory setting, that is beyond most of us.



Beakers, stir bars, stir plate, lint free kim wipes, rinse bottle, and a waste cup.



Lint free wipes. beakers for buffers, rinse beaker, stir bars. Yes they color coordinate to the same color pH buffer solution.



A beaker that has a vortex, which is WAY too much. pH should be stirred gently. Never let the stir bar impact against the probe.

Any lidded cup can serve as a storage beaker for a probe submerged in KCl storage solution.
Color coded buffers. The colors are universal. Buffer 7 is always yellow.
And a wash bottle filled with DI water.

How to 'ghetto' the set up:

Beakers: baby food jars, any small stable glassware. All super cleaned, with no residue or smell.
Rinse cup: A giant yogurt, or sour cream tub will do. For dumping the used solutions, and rinsing probe between readings.
Wash bottle: A yogurt cup and a plastic pipet will do just fine.
Storage beaker: Cut a hole in a lidded container large enough for the probe.
Stir plate. DIY video's on You Tube. Cost about $15-20. The Hanna stir plate above, I believe, was $60-80.

Remember to keep everything super clean. Rinse in tap water, rinse in DI a couple times, place on paper towel to dry, beakers placed upside down.

Nice lookin gear there! You should look online for a few of those things for cheap and post the links!

Everyone just assumes that stuffs cheap but if the stirring plat is only 60-80 for the good one thats pretty cheap.

Amazon and ebay have good selection for less than a scientific supply co. Maybe accumulate over time.

The beakers for buffers should be 'designated'. Use a big sharpie marker, and mark them 4, 7, 10, 6, or whichever you use.
Rinse after each use and keep together with the coordinating color stir bar. Careful not to loose the stir bars down the sink. LOL

I think the homemade stir plate is a cool idea, and it looks like it would work just fine, if one was handy with the tools. Might even try it myself.

Store the buffer solutions in a cool area. Away from outside walls, hot lights, and any other source of heat, or heat fluctuations.
Most buffers are recommended to store at 20-25 dgC, which is a cool 70-75 dgF room temp.
The cooler you keep the buffer, consistently, will make it less likely to go bad before it expires.
If you cant get the calibration or the readings to stabilize, the buffers may be to blame, rather than the probe.

Doer said:

Update. Pen swapped and tested before out the door. Friendly, neighborly Hydro Store.

Can't do that online, now can we, boys?

Click to expand...

Update: Pen swapped up for the $190 Hanna Combo. The BL is not a very fast reading pen. The temp sensor is not exposed. It's in a housing on the BlueLab. I can calibrate the Tri-meter, (remember the temp probe is the EC, gotta use both) and calibrate the BL, take them out and rinse, then I can put them both in fresh solution and the Tri-meter is fine and the BL will wander around for 60 seconds or more and still settle .4 off. Then move it and it's .6 off.

The Hanna Combo is faster and more steady, calibrates easily and holds calibration well. The probes are replaceable.

That's a plus.

It is important to have a system that you are confident in. So, I'm real happy you found one.
I had the feeling that BL may not yield the best precision, but great as a back up if you factor in the correction (error).

Sometimes, meters need to go through the calibration process a few times to 'find themselves'.
Seriously, when I had a bouncing around issue, I'd start over once or twice to work it out.

Run a 'side-by-side' when calibrating and reading samples for a week or two.
If it stabilizes, great. If not, you'll know how to correct for it.

The temp sensor might be in the pH bulb. Many are made that way.

Oh the joys of the weekly farm box.

I couldn't resist sharing, but, now I feel a little dirty.

In another thread I answered someone that was trying to test the pH of 'colored' water using a color comparator system.
I decided to rewrite my advice here for those that wish to understand. And I'll try to keep it simple.

• Use a small, very clean jar with a cap. Preferably a tall, rather than wide jar.
  Soil: Add a tablespoon or two of the soil, add water to above soil.
  How much do you need for the test? That is how much liquid you should have above the soil line.
  Shake vigorously. Place sample on table (wherever), and let sit for 1 hour.
  After an hour the solids should have settled to the bottom.
  Don't stir or shake.
  Pour the supernatant (water above soil line) into your tube for testing.
  Keep the sample at a constant temperature.
  
  Runoff and Nutes: may be tested as-is, or using the above procedure if there is heavy solids material.
  As long as the runoff is not oily, it should work. Just let any solids settle out.
  
  This is as close as I can come to a decent testing method without getting more complicated.
  Doing a color comparison test on tinted fluids will be guess-timating.​
  
  
  Of course, ideally, one would test with an ion electrode probe, so that the color of the sample does not interfer with the result.

Upon receiving a new pH meter or probe, it must be cared for ahead of use. Most new equipment needs to be acclimated and maintenanced right out of the box.
If you experienced problems with a pH meter that is new, this may be the reason.

Visually inspect the probe for damage, both internal and external.
Ensure there is adequate filling solution (internal).
Do an initial set up on the equipment. Ensure that it is turned off.
Prepare a place for the probe to sit idle in storage solution
Let it sit, in the environment that it will be kept, for 24-72 hours. This accounts for the normal ambient temperature fluctuations.
Use an alternative source for any testing that is needed.
Following the manufacturers instructions, clean the probe. Use temperature acclimated water.
Run the calibration sequence with temperature acclimated buffers.
The calibration sequence may be run again, as it may take more than once to get the instrument to settle.
Place in storage solution, and let it sit.
Test the pH of a couple samples. If you suspect the reading may be off, use another probe, pen to double check.
If any inaccuracies, or malfunctions occur, refer to the manufacturer for troubleshooting.
This is the point when you either have confidence in the readings, or have identified an error in the readings.

I've been keeping an eye on posts concerning pH measurement. So I just had a couple comments to make to keep this thread up to date.

Most growers do not purchase expensive pH meters. Many use the very inexpensive hand held pens and replace them as often as necessary. You either love em or hate em.

On a grand scale, a $30 pen can be as effective as a $150 meter. Remember that pH meters can cost many hundreds of dollars, and be highly accurate, with the probes costing several hundreds of dollars a pop.

It is much more cost effective to occasionally replace a simple pen, than to overpay. As growers, we like to keep it simple when we can. pH is important, for sure, but it can be simple too.

Well, since this thread stated, I have purchased a Hanna for $200 that doesn't work either. It won't calibrate, they will send me a new probe end. At least it is replaceable.

I first bought a Tri-meter for $200. It is really all you need. Dunk both probes into the sample for getting the temp for the pH probe to use and get an instant result.

All these pH pens I have tried are dog slow, and still squirrelly, compared to the plugged into the wall, trusty Tri-Meter with big read outs.

Probes are $30, but last forever if you keep them in solution.

A good investment for you, and many others.
Reliability is worth the money.
If you find something that works for you, stick with it.

technician09 writes: I have recently switched from numerous digital ph pens to the ph drops from General Hydroponics. I've noticed after 5-10 minutes the colour changes from when it is first tested. Are you supposed to read the colour as the drops are added or do you wait until the vile has stopped changing colours? I know I will get some responses stating to use a digital meter but I have found them to be to high maintenance and fragile. (I have tested a few popular meters freshly calibrated with ph7 and in the same water and they all had different readings)

Click to expand...

Firstly, remember that pH is considered an 'immediate' test. That means you can't let it sit. It is meant to be added and read immediately. Add the drops to achieve a color change and take the first reading. Don't let it sit for 5 or 10 minutes and try to take another reading. The time will cause a continued reaction of residual compounds. You want to take the initial measurement when the reaction is at its strongest.

The temperature interference will occur when the (pH drops) is a different temp than the sample you are testing. They should be within a couple degrees of each other. Although the pH drops are likely meant to be used at 20 degrees Celsius (about 68-72 degrees Fahrenheit).

Also, meters will give varying results. The reason for this is that each one has a range of accuracy from the manufacturer. One could inherently be -1.3 pH units, while another could be off by +0.7 pH units. Add in the normal biases of measurement, and it becomes understandable.