Add pH and EC calibration step to the initial Setup [RESOLVED]

Something that I have noticed that seems to be a common issue with first time growers is the pH and EC probes need to be calibrated. It might be a good idea to add the calibration to the initial setup of the Grobo, or add it as a step when starting a new grow.

And maybe include some 7.0 pH and EC calibration juice with all new Grobo’s? It could prevent some heartache when a plant is in rough shape simply because the pH probe needed to be calibrated.

Tagging @bjorn and @Stephen


I second this motion


Thanks for the feedback @VermontGrobo! I’ll bring the idea up with our team next week.



  • (BrilliantIdea): [:brain:] [:bulb:]


- - - [2021-07.30]:

  • ([RESOLVED]):



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That is a great idea, wasted a bottle of #1 and plant was so alkaline it stunted growth, might help too if PH levels were sent to us.

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Having end-user access to the sensor data is the critical missing piece, here.

It’d be really easy to tell if your sensors required calibration if you could, you know, see the data.


I agree with the sentiment that we should have access to the data, very strong supporter of this. But, I don’t think it’d help with calibration on it’s own – we would still need a 2nd probe/meter to confirm it’s in need of calibration, or we would still need to just perform the calibration to see if it’s changed if we don’t have a 2nd meter to verify with.

I’d expect with an incorrectly calibrated probe, we’d put in water with a pH of 8.7 (for example) and maybe it’d report that the ph is 6.2 and A-OK. So “the data” would say 6.2 at this point but the water has a pH of 8.7! Once calibrated, “the data” would say 8.7 to match the water. Until the calibration was actually performed, the data didn’t give us any indication it needed this.

Now, if we have a standalone pH sensor and actually know what the pH is - that’s another story, we can confirm that the number the grobo reports is the same number the 2nd meter reports. But, not all meters are created equal and there’s a chance that users would jump to the conclusion that the pH is wrong when really it’s a problem or difference with the meter. Using the calibration solution avoids that issue entirely.

Technically, both of those pH probes should’ve been calibrated with the solution, as one or the other might drift from its baseline in different directions over time. Unless they’ve both been freshly calibrated with solution (and using new batteries, if handheld) then using one to calibrate the other might throw them both off. So again, calibration solution avoids an issue.

Having two probes might give an indicator that calibration is needed but it could be a false alarm simply because the probes are from different brands.

But, if we saw in an event log that usually (let’s say last week) the machine doses 3 shots of pH down over the course of 3 hours after filling with new water, but this week it used pH up instead of pH down and there was no change in the water source – that would be an indication of a difference in trend that would either mean the water source is no longer the same pH as it was before or that the probe needs calibration. This is the data I’d like to see, as much if not moreso than the raw values from the sensors. It’s often the “other things” that result from something being wrong that are noticed before the problem itself, which is especially true with pH but extends to other things like temperature and RH as well.

Only mentioning this as I’d really hate to see everyone requesting the raw values when it’s the event logs (or graphed time series data) that’d really help us to self-diagnose!

I also think that the units should come with a water temperature sensor, or that users should be strongly encouraged to pick up the calibration + external sensor upgrade when purchasing. Distilling the info from the forum here into a “new user guide” would be helpful too, to get users up to speed faster on things they should be watching for (both positive and negative).

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Don’t they already come calibrated when you first buy it? That is what I am thinking as I dont have anything to calibrate them yet. Mine should be here by next week I hope.

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They do, however some growers have run into issues. It’s electronics, things happen. I do believe that the unit is sent with some calibration solution to alleviate these issues and allow the user to calibrate before the first grow. This was not the case when I first started with Grobo but I believe it was changed due to the issues arising. @Todd.grobo, can you confirm?


Hey growers,

Here is the latest update for ya’ll!!!

We factory calibrate both the EC probe and the pH probe. We do include calibration solutions for you just in case your unit is in need of a ‘reminder’ of what the calibration points are.

You won’t need to recalibrate EC unless you have a broken probe or have replaced a board in your unit, in which case the support team will jump on a call and calibrate your EC probe with you. A 2.77 solution is included in the pH and EC probe care kit.



@Stephen for the win!