PPM dropping in water tank. Any ideas?

Hi guys,

I'm currently running a gravity fed system (Autopot) linked to a 100L flexitank.

I mixed up 50L of nutrient solution about 5 days ago, the ppm of the solution was between 840/980 when mixed (as shown on the Blue Lab Truncheon).

I've checked it again this morning and it's now sitting at 700ppm.

I have a dual outlet air pump with 2 air stones in the tank, everything should be mixed and we'll oxygenated.

I'm running Canna nutrients, Coco A + B, CalMag, Cannazym + Boost.

Is this going to cause me issues?

Thanks guys!

MBS

IMG_20200510_124549.jpgIMG_20200510_124542.jpg
 

jondamon

Well-Known Member
Trying give your tank a good mix up.

you could even have some precipitation of nutrient ions falling out of your solution.

check for sediment in the bottom of your tank.
 

jondamon

Well-Known Member
Hi guys,

I'm currently running a gravity fed system (Autopot) linked to a 100L flexitank.

I mixed up 50L of nutrient solution about 5 days ago, the ppm of the solution was between 840/980 when mixed (as shown on the Blue Lab Truncheon).

I've checked it again this morning and it's now sitting at 700ppm.

I have a dual outlet air pump with 2 air stones in the tank, everything should be mixed and we'll oxygenated.

I'm running Canna nutrients, Coco A + B, CalMag, Cannazym + Boost.

Is this going to cause me issues?

Thanks guys!

MBS

View attachment 4560988View attachment 4560989

I’ll bet that if you drop the ZYM and then BOOST your yields would stay the same.
 

Renfro

Well-Known Member
FWIW take readings on the 0.5 scale as thats what we generally speak here.

You are sure you werent reading the .7 scale before and the .5 scale now?
 
Interesting; I would think a device like that would need to be calibrated...but I guess not. Obviously I don't use one...I was just trying to brain storm a bit. Anyhow, good luck friend.
It's a valid point, it could do with a clean...but it usually gets a rinse after being used, there shouldn't be much of a nutrient build up! I'll give it a go in the morning, cheers man.
 
FWIW take readings on the 0.5 scale as thats what we generally speak here.

You are sure you werent reading the .7 scale before and the .5 scale now?
That's interesting Renfo, thanks for the heads up. I'm using the Canna feeding schedule at the moment, as attached below...I'm absolutely sure I wasn't switching between .7 and .5, there's definitely been a drop in PPM. I gave the tank a good mix earlier and it's sat at 500PPM on the .5 scale.

Any suggestions on how to get it closer to 896?

Thanks - MBS
 

Attachments

jondamon

Well-Known Member
I would assume that the nutrient solution is being distributed equally with it being a gravity fed system...I can't see that PPM could drop using this method. It's baffled me!:?
Does any of your water out of the reservoir go through the plants and back into the reservoir?
 

Renfro

Well-Known Member
Did the temperature of the water change while the PPM was dropping? Not even sure if the truncheon has ATC. That would make for an EC reading change as the solution changed temperature, say warming up from air stones.

For example, I have a PPM meter thats very accurate, reads stuff like 1098 PPM and you can watch it change as the temperature probe adjusts to the solution temperature (you can see the temperature reading). So as the temperature compensation accounts for the solution temperature, the PPM reading slowly changes too.
 

Renfro

Well-Known Member
Ok in the truncheon manual it says to let the probe adjust to the solution temperature so it does have ATC. Are you allowing this enough time to happen? 1-2 minutes according to this:

bltruncheon.PNG

If you are allowing it the time to adjust and temperature compensate then perhaps the temperature sensor in the unit is faulty and not compensating for the temperature of the solution.
 
Ok in the truncheon manual it says to let the probe adjust to the solution temperature so it does have ATC. Are you allowing this enough time to happen? 1-2 minutes according to this:

View attachment 4561503

If you are allowing it the time to adjust and temperature compensate then perhaps the temperature sensor in the unit is faulty and not compensating for the temperature of the solution.
Renfo, thanks for your brilliant advice, it's really appreciated.

PPM was still way down this morning, even when letting the Truncheon warm up for a few minutes. I've added some more Canna A + B to bring PPM back up, it's sitting consistent at 800PPM now.

The girls are looking very healthy so I'm not going to worry too much at this point, this one remains a mystery!:cool:

Once again, thanks for your time!

MBS

IMG_20200511_191743.jpgIMG_20200511_191749.jpgIMG_20200511_191802.jpg
 

jondamon

Well-Known Member
Renfo, thanks for your brilliant advice, it's really appreciated.

PPM was still way down this morning, even when letting the Truncheon warm up for a few minutes. I've added some more Canna A + B to bring PPM back up, it's sitting consistent at 800PPM now.

The girls are looking very healthy so I'm not going to worry too much at this point, this one remains a mystery!:cool:

Once again, thanks for your time!

MBS

View attachment 4562399View attachment 4562400View attachment 4562401
I have that same RAM humidifier.

great little cool mist humidifier.
 
Hi guys,

I'm currently running a gravity fed system (Autopot) linked to a 100L flexitank.

I mixed up 50L of nutrient solution about 5 days ago, the ppm of the solution was between 840/980 when mixed (as shown on the Blue Lab Truncheon).

I've checked it again this morning and it's now sitting at 700ppm.

I have a dual outlet air pump with 2 air stones in the tank, everything should be mixed and we'll oxygenated.

I'm running Canna nutrients, Coco A + B, CalMag, Cannazym + Boost.

Is this going to cause me issues?

Thanks guys!

MBS

View attachment 4560988View attachment 4560989
Hi,
I had the same issue with you the reason why it’s happens is because the air pump it will increase the ph up and drop the level of ppm.Use the air pump one hour before feeding the plants and try one reservoir per feeding.
 
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