Grow Mediums pH in tray is much lower than in res

[briefbriefs]

Has anyone encountered this issue? The pH in my res has always remained at a steady 5.9-6.1 but i just checked the tray and the water in the tray (that has been sitting in there no longer than 1.5 hours) has a pH of 5.5. What could be causing this?

Im feeding Mega Crop at 4g/gal. Thats it.

 

[Bob's Auto's]

Probably the binding of Calcium out your nutrients into the medium.

 

[briefbriefs]

Probably the binding of Calcium out your nutrients into the medium.

interesting! is this something i should be concerned about / can do about?

 

[Bob's Auto's]

What is the medium in your autopot?

 

[briefbriefs]

What is the medium in your autopot?

Coco with 40% perlite. Coco is by Biobizz and it came pre-hydrated in a bag.

 

[Proph]

There are a handful of variables that could be causing that to happen. I can't think of a situation where the ph in the tray would matter. I wouldn't worry about it. The ph is naturally adjusted in the rhizosphere.

 

[briefbriefs]

There are a handful of variables that could be causing that to happen. I can't think of a situation where the ph in the tray would matter. I wouldn't worry about it. The ph is naturally adjusted in the rhizosphere.

Ah, Proph! Thank you!
(side note: your username always reminds me of my great uncle who everyone used to call "Profe" because he was smart as hell and everyone went to him for advice [he also had a phD in mathematics lol])

 

[Bob's Auto's]

Like I said. Probably the medium (coco in your case) that's binding the Calcium in your nutrients.

 

[Olderfart]

Has anyone encountered this issue? The pH in my res has always remained at a steady 5.9-6.1 but i just checked the tray and the water in the tray (that has been sitting in there no longer than 1.5 hours) has a pH of 5.5. What could be causing this?

Im feeding Mega Crop at 4g/gal. Thats it.

If you mean by tray the water that sits in the space where the autovalve sits, I don't think the change is from binding to your medium - the water/nutes in there have not seen the medium yet, so I doubt that the medium is the culprit. What is your water source, and what is it's starting ppm/EC? Do you use an air stone in your reservoir? There may be something going on with your water and how it reacts with the change in environment between the reservoir and the lines/tray. At any rate, it seems that your coco is receiving pH5.5, not what you intend, so if I were you, I would chase it down if you can.

Good luck with it.

 

[briefbriefs]

If you mean by tray the water that sits in the space where the autovalve sits, I don't think the change is from binding to your medium - the water/nutes in there have not seen the medium yet, so I doubt that the medium is the culprit. What is your water source, and what is it's starting ppm/EC? Do you use an air stone in your reservoir? There may be something going on with your water and how it reacts with the change in environment between the reservoir and the lines/tray. At any rate, it seems that your coco is receiving pH5.5, not what you intend, so if I were you, I would chase it down if you can.

Good luck with it.

I use tap water which comes in at 43ppm-55ppm depending on the day. No air stone in my res, but do use a water pump on 15min intervals every 2 hours. I also use a Torus Hydro Perfect pH which is basically just this tube of what looks like salt that keeps my pH at exactly what i want in the res. I thought that PERHAPS the nutes were falling in pH once they left the res, so i did a test and put some nutes for a little over an hour in a cup and then measured that vs the res and they were at the same pH. So there goes that theory.
Also, last night i checked the pH inside the res and inside the trays and they were only 0.1 or 0.2 off from the res -- however the trays were full of nutrient solution. This morning i checked my half-full trays again and the pH is at 5.6 again (res is at 6.2) and the ppms are about 35 higher than my res. What could be happening?

ps: i have a hanna instruments ph/ppm/ec/temp reader which also has a calibration check capability, so i know for a fact that its perfectly calibrated.

Edit: i just realized that perhaps the air pump that runs to the air dome in the pots is causing the shift in pH. Would that stand to reason?