A few questions and a few statments

I know I commented on some PH and EC meters in one of the treads lately. I've had all kind of meters and I bought a Bluelab combo meter a few years back and really liked how it preformed. Last time I checked it it was off several hundred ppm around 300. I couldn't get it to calibrate any closer, so I bought a few cheap ones off Amazon that you could calibrate and they worked well, but I just don't trust the cheap ones so I would calibrate every time. That gets old!
I picked the Bluelab up about about a month ago and just added 300 extra ppm to my final mixing. I've been having some deficiencies lately so I brought it in the house to try to calibrate again. My ppm solution is supposed to be 1977 using .7 conversion. I checked it it read 625 WOW I'm starving my plants! So I cleaned the hell out of it got it to read 1625 was the best I could do. I accidentally knocked the cup of the calibrating solution over, so I poured another cup and it read in the 1400.
I brought this solution in from my shop which is a 45 degrees so I put cup in front of heater for a few minutes to bring to room temp and it jumped from 1400 to 1968. So when mixing nutrients in cold water do the nutrients act same way? I always pour my nutes in a squirt bottle and mix accordingly with my meter. I think I might switch back to measuring my nutes.

rollyouron said:

I know I commented on some PH and EC meters in one of the treads lately. I've had all kind of meters and I bought a Bluelab combo meter a few years back and really liked how it preformed. Last time I checked it it was off several hundred ppm around 300. I couldn't get it to calibrate any closer, so I bought a few cheap ones off Amazon that you could calibrate and they worked well, but I just don't trust the cheap ones so I would calibrate every time. That gets old!
I picked the Bluelab up about about a month ago and just added 300 extra ppm to my final mixing. I've been having some deficiencies lately so I brought it in the house to try to calibrate again. My ppm solution is supposed to be 1977 using .7 conversion. I checked it it read 625 WOW I'm starving my plants! So I cleaned the hell out of it got it to read 1625 was the best I could do. I accidentally knocked the cup of the calibrating solution over, so I poured another cup and it read in the 1400.
I brought this solution in from my shop which is a 45 degrees so I put cup in front of heater for a few minutes to bring to room temp and it jumped from 1400 to 1968. So when mixing nutrients in cold water do the nutrients act same way? I always pour my nutes in a squirt bottle and mix accordingly with my meter. I think I might switch back to measuring my nutes.

Click to expand...

Yes, ec and ph meters are effected by water temp. If my water temp is in the 40'a, it sometimes takes more than 3 minutes for the ec meter to settle on a number. My ph meter seems to be a little quicker, but I don't trust it in less than 1 minute.....

The majority of EC meters are accurate at 25°C. The thing is, EC is only an estimation of TDS. EC varies based on the ions in solution and also varies based on TDS. That is, the relationship between EC and TDS is not actually linear.

On top of that, there are different conversion factors depending on if you are using an American standard or a European standard.

MisterBlah said:

The majority of EC meters are accurate at 25°C. The thing is, EC is only an estimation of TDS. EC varies based on the ions in solution and also varies based on TDS. That is, the relationship between EC and TDS is not actually linear.

On top of that, there are different conversion factors depending on if you are using an American standard or a European standard.

Click to expand...

He did say he's using .7 scale
Bluelab has temp correction technology.

Dumme said:

He did say he's using .7 scale
Bluelab has temp correction technology.

Click to expand...

If the TDS conversion from EC jumped from 1400 to 1968 when water temp changes from 5°C to what ever it rose to, then temperature correction is either not working or was never there in the first place.

I'm guessing, bad reading, human error, needs calibration, or low batteries. No offense to rollyouron.