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Buying Used PH Meter?

5

5cooby Doo

Member
I found local guy selling Blue Lab Guardian for me for $125USD. He saying it's 2year old and he always keep it stored in water. (so that's good I know he stored it correct.)

Is there anything I should know for buying this one used..anything to check out specifically? Or it's good deal if it's working?
 
Mikell

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
Lowball 100.

If the EC meter reads correctly (I would bring solution) you can always grab a new pH probe. If it is close it likely just needs a cleaning as per instruction and that knobby paste.

Been using the same one for 4 years.
 
5

5cooby Doo

Member
Thanks Mikell.

I don't have any solution to test it. What kind of solution? Like a PH 7 and PH4? Or just any nutes?

He wanted 155USD, I told him 125USD. Cheapest I could find it at the store is 310. So basically half price.
(I converted to USD prices because most of you guys are from U.S. I noticed.)

I was just worried about any problems it may have...he stored it correctly and he says its working.
 
Mikell

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
Ideally you can see it function. If he doesn't have the EC, pH 4 and 7 calibration solution, bit of a red flag. But really, unless he's a monkey and has broken the EC probe I would snap it up at 125USD.

The EC probe isn't calibrateable per say, you clean the probe until it reads the same as the solution.

Most deviations on the pH reading can be corrected with 24hrs in KCL storage solution.

The only Bluelab care products I buy are the KCL and the EC probe cleaner. The calibration solutions is half the price for other brands.

Stoned rambling.
 
5

5cooby Doo

Member
AHH! I was going through manual for Guardian.. it says only part that EVER needs to be replaced is the PH Probe.

..so as long as everything else is good, It should be fine. Maybe I'll try to bring down price more.... as I was reading it should NOT be stored in distilled or RO water... only in the ph7 solution. So I have to make sure what guy was using to store in.
 
Mikell

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
I leave the probes in the reservoir or a cup of nutrient solution. Our tap is usually 20ppm.

It was my understanding the probe will deviate towards any solution if left long enough (or lose ions to distilled/RO) and to periodically correct with KCL. I have yet to see this and just clean/calibrate every 2-3 weeks and store in KCL for 24hrs every other month.
 
5

5cooby Doo

Member
Mikell you ninja'd me on your second last post, did not see it after posting mine lol.

He said he should have some solution left so he'll test it tonight and let me know. Hopefully it works.
I don't want to lowball, he was reasonable with the negotiating, and there's not many used ones around locally.

Meadowman, well if yours is still good it should be fine. He said to me also, as long as it's kept wet it's fine. But said he will test. He had it in a water bottle -water.
...... if you're running it for a grow, at least 3 months it's in water.... so I mean can't be to bad stored in regular water right. (worst case I need a new PH probe, still not a bad deal compared to brand new price.)

The manual said use EC probe cleaner Or dish detergent (With a soft toothbrush or your finger), so you might just save a couple more bucks there, Mickell. You sure take very good care of your unit sir! Kudos to that!

You're also right I believe, where it will deviate to what it is left in.. think I read that in there to somewhere.
 
gaiusmarius

gaiusmarius

me
Veteran
you just need it to read correctly for at least the ph 7 calibrating liquid, ideally test it in both the ph 4 and ph 7 liquid. you can buy a small sachet with 25 mils of each, just enough to test that it's working. although buy a small bottle of each will be best to keep it calibrated in future.
 
5

5lrootsexcel

New member
A new ph probe is around $45 so even if the one included is busted, you get a working unit for under $200.

You're not supposed to store the ph probe in water. That includes tap. Store it in the storage solution because water will cause the salts to basically elute out and your ph readings will no longer be accurate.
 
5

5cooby Doo

Member
The guy was very nice. Even gave me the ph7 and ph4! It tested the ph4 at 4.1, so not bad at all... maybe just needs a cleaning and recalibration. And the EC/PPM was reading fine as well.

I picked this up for storage solution. (To be honest I got slightly confused, thought it was EC calibrating solution, but wanted storage solution either way.) This is for my PH Probe right? https://grotek.com/product-detail/electrode-storage-solultions/

..And the EC Probe does not need to be left in any liquid? But it will need a different solution for calibrating it than that ph probe storage solution?
 
Mikell

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
That is a normal reading unless he just calibrated it.

Yes, that is for the pH probe. Looks to be the same as the Bluelab solution based on the decomposition section of the MSDS. Whether the same strength I do not know.

The EC probe is more robust and can be left in or out of the reservoir. Doesn't matter if it dries. Google the care guide.

It does need a separate solution to calibrate. The Grotek version is the "1000ppm TDS" solution. This is for the 500 scale. An EC reading would be 2.0 mS/cm.
 
5

5cooby Doo

Member
Was just hoping to get your opinion on this one to.... with the 1000PPM solution, (ppm x500 on the bluelab), it is measuring that as 1200PPM (ppm x500). Does that mean ppm pen part is bad, or is that somewhat normal?
 
Mikell

Mikell

Dipshit Know-Nothing
ICMag Donor
Veteran
Probably just needs a cleaning, repeat until it reads withing 50ppm.
 
5

5cooby Doo

Member
Oh thanks mate! I did clean with finger and soap (it said in manual was okay.) But maybe I should get recommended tooth brush and cleaning product to do it properly. I will try and report back. :)
 
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