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Salty truncheon

Ca++

Well-known member
Just tested a bluelab truncheon. You might think why? with an auto-calibration meter. However, it missed by a third.

1g of table salt, in 1 liter of water, is 1000ppm on the 500 scale.


Or my meter was right, and it's me that's broken
 

dramamine

Well-known member
Just tested a bluelab truncheon. You might think why? with an auto-calibration meter. However, it missed by a third.

1g of table salt, in 1 liter of water, is 1000ppm on the 500 scale.


Or my meter was right, and it's me that's broken
Man, it's strange but I ran a Bluelab truncheon for 7 or 8 years with no problems at all. Finally had to replace it, and now I've gone through 3 replacements for it, through warranty, because all of them began giving false readings in short order. Seems to me they aren't as bulletproof as they once were. That, or my luck is truly terrible.
 

Ca++

Well-known member
I should of got 2.0 plus my tap of about 0.3
I got 1.7
I didn't check another I use, but know it reads about 0.2 lower (so 1.5 not 2.3)

When you read your plants, and just count the lights to repeat what you know, the calibration doesn't matter much. I did this after a second crop not using one. Making a bucket up each day, is more about following the plants than the numbers. Though I wanted to see some numbers, as I was running above book hydro, in a rich high peat compost. Not for the first time, but barely in living memory.

The gap between my meters narrows as the EC rises. It's a difficult comparison. There is a cleaning procedure with unperformed cream cleaner, and some rag. Not even 5000 grit, though I might be tempted.

I'm hopeful that someone else tries it. It would be nice to have a reliable way of making a quick check solution. The internet seems to agree its right.
 

dramamine

Well-known member
The saltwater calibration solution works like a charm. Nice one. Now to find a diy ph calibration solution.
 

Ca++

Well-known member
If you are up for it, you can have a go here
That page shows how to mix two powders with water, to make a solution around 7. There are two grey sliders to set the pH you want, and it says how much of each to use.
Under a tab further down, you can pick other ranges. Such as an acetate buffer that can do a 4

Might need some good scales. For example, the 4 needs 1.861g of one powder, per liter. So for a more reasonable 100ml.. well you can see where I'm going. 100ml is a bottle full, and you won't keep it long. Mixing 25ml... 0.046525g

The pH7 needed about 8g of each powder per liter. Much easier weight to work with. The 4 can be made quite a few ways, so it's perhaps a case of finding one that works. Or offers an acceptable error, with what you have.
Realistically, you are not using the pH someone told you, but rather one you found works for you. In which case, you just need repeatability, rather than absolute precision. Lets say, you used 2g instead of 1.861g. You still make a 4.0 which is 0.2g in 100ml, or 0.05g in 25ml, and 0.000 scales are $10 now. You have to use 2.227g per Liter before you have a solid 4.1 so it can be done. Even with cheap powder scales, that miss by 10%
 
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