Calibrated Bluelab Equipment showing different EC's / pH's

Hey Guys,

I'm having some weird issues, or maybe it's me? I thought bluelab was the best equipment out there, so I bought myself a couple of pH dosers and some guardians....

Now the first issue I had was with my first guardian which I'd been using for about 2 years. I noticed my new plants were getting nute burn, but the EC was only 0.6. I bought a second one as a spare and hooked it up and found the EC on the new one was showing 0.8 in the same solution. I got out my ppm calibration solution and double checked both units, the new unit was perfect, but the older one was definitely out. There is no way to calibrate the EC probe of the unit, so I threw that unit in the bin. Not happy.

I also have two pH dosers that I use to dose pH and down. Now this is the main issue that is confusing me and is messing with my OCD.

I did the calibration on all 3 units. Cleaned the probes with RO water, immersed them in 7.0 pH calibration solution and calibrated them to 7. I then cleaned them and did the same thing with 4.0 pH calibration solution. Powered then off and on, then cleaned the probes in water, dipped them in both 7 and 4 pH solution (cleaning them with water between) and they're perfect. They all read 4.0 and 7.0.

Now this is where it gets strange (or maybe I'm doing something wrong??)

When I put them in my 1000L nutrient tank ALL 3 show different readings! They're all placed in the same area of the tank. The tank has a pump that pumps fluid from the bottom of the tank and sprays it back in at the top, so the solution is always moving. I'm using both their temp probes as well. I have tried both earthlink on and off but still different readings on pH.

The solution in the tank is made from RO water, but I always add cal-mag up to EC 0.4 and then have added my nutes to take it up to EC 0.6

Any idea why I'm getting 3 different pH readings?







Justin.

I will say that my Bluelab Combo meters suck. They have gotten me by, but both read different. I hate how you cannot calibrate the PPM meters.
How long are you letting each probe sit in the calibration solution before calibrating it?

How old are the probes? They dont last forever.

The PH probes are just at the end of the first grow.
The PPM probe is what sucks about them.
Get a Hanna

5BY5LEC said:

I will say that my Bluelab Combo meters suck. They have gotten me by, but both read different. I hate how you cannot calibrate the PPM meters.
How long are you letting each probe sit in the calibration solution before calibrating it?

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Hey. I'm letting the probe sit in the solution for 2-3 minutes until the ph reading stops moving.

Larry3215 said:

How old are the probes? They dont last forever.

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The current 3 are all new equipment, about a month old (since I started my grow) how long do they last? They're also quite pricey to replace.

5BY5LEC said:

The PH probes are just at the end of the first grow.
The PPM probe is what sucks about them.
Get a Hanna

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Do you have any links to the Hanna products?

I love it when my ph meter gives me a different reading every time for the same nute solution..I guess you just keep testing until you get a reading you like. I've had a couple junk ph meters and they won't give the same reading back to back.. That's why I still use drops.

70's natureboy said:

I love it when my ph meter gives me a different reading every time for the same nute solution..I guess you just keep testing until you get a reading you like. I've had a couple junk ph meters and they won't give the same reading back to back.. That's why I still use drops.

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Ha Ha... it's killing my OCD! I guess as long as all 3 are showing between 5.8 and 6.2 in hydro then I'm ok.

70's natureboy said:

I love it when my ph meter gives me a different reading every time for the same nute solution..I guess you just keep testing until you get a reading you like. I've had a couple junk ph meters and they won't give the same reading back to back.. That's why I still use drops.

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This is why I say what I said about the meter. I find myself double checking a 250 dollar piece of equipment against a 5 dollar drop kit, that I know will give accurate results.
The ONLY good thing about the meter is that is it submersion, so I only have to walk in and press a button or two. No taking water samples.
But again what good does it do, when you always question the readings.

Justin Freidman said:

Hey. I'm letting the probe sit in the solution for 2-3 minutes until the ph reading stops moving.



The current 3 are all new equipment, about a month old (since I started my grow) how long do they last? They're also quite pricey to replace.



Do you have any links to the Hanna products?

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https://hannainst.com/hi9814-ph-ec-tds-multiparameter.html
I have personally used one of these when I take care of my buddy's grow when he is away.
Love it.

I use this one, sensors are getting more readily available for cheaper these days. Just keep the calibration solutions in sealable containers and check them often for accuracy. I haven’t had any issues with this one yet and it’s a very great price.

Search in amazon for: B07H161MPL

Thanks guys, will check them out. The issue is that my grow room is an hour away and I remotely control everything / monitor via camera, so I'm looking for a permanent display EC/pH meter.

Justin Freidman said:

Thanks guys, will check them out. The issue is that my grow room is an hour away and I remotely control everything / monitor via camera, so I'm looking for a permanent display EC/pH meter.

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That is pretty cool. I joke with a friend sometimes about having valves and stuff remotely controlled with servo's.
https://scienceinhydroponics.com/2017/05/a-simple-arduino-based-sensor-monitoring-platform-for-hydroponics.html
Get a BT unit to control it from your smartphone haha.
Just some stuff to think about.

5BY5LEC said:

That is pretty cool. I joke with a friend sometimes about having valves and stuff remotely controlled with servo's
https://scienceinhydroponics.com/2017/05/a-simple-arduino-based-sensor-monitoring-platform-for-hydroponics.html
Get a BT unit to control it from your smartphone haha.
Just some stuff to think about.

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When I have some time, I'll send some pics of the entire setup. I'm just finishing up the drain to waste tanks (3 x 1000L) the idea is mix everything up then only need to visit maybe one a month. I'm away for Xmas so preparing everything to run while I'm away.

My room is an hour drive away but has internet connection, I remotely monitor everything via camera and use remote units to operate pumps, etc.

Do you let them temperature adjust? I use the BL Trimeter, and it takes up to 5 minutes to fully adjust properly.

SSHZ said:

Do you let them temperature adjust? I use the BL Trimeter, and it takes up to 5 minutes to fully adjust properly.

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Yes buddy, the room is 25 degrees and all liquids in it the same. BL trimeter? This is the guardian right? Yes, I have one of those and two x ph dosers.

5BY5LEC said:

This is why I say what I said about the meter. I find myself double checking a 250 dollar piece of equipment against a 5 dollar drop kit, that I know will give accurate results.
The ONLY good thing about the meter is that is it submersion, so I only have to walk in and press a button or two. No taking water samples.
But again what good does it do, when you always question the readings.

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What drop test do you use? My ph pens, not your pricey one, just went bonkers and one is brand new. I have ph strips from my friends biotech lab that work great but it's not an endless supply and I bet they're pricey as well.

Just the GH one that came with the ph kit.
They sell test strips on Amazon that are in a specific range say ph 5-8 that are really easy to use. They come on a big roll for 15 bucks or so.