Grow Mediums pH in tray is much lower than in res

[Bob's Auto's]

Does it smell foul in the trays? Because the only time I had the pH in my reservoir get more acidic is when I had a problem with anaerobic bacteria. It gave a foul smell and only went away after I emptied the reservoir and cleaned it, the tubing and anything that was inside the reservoir with Hydrogen peroxide.

 

[briefbriefs]

Does it smell foul in the trays? Because the only time I had the pH in my reservoir get more acidic is when I had a problem with anaerobic bacteria. It gave a foul smell and only went away after I emptied the reservoir and cleaned it, the tubing and anything that was inside the reservoir with Hydrogen peroxide.

Nope! no foul smell that i can discern... i also use an enzyme product (Flying Skull z7) and a HydroGuard analog that are supposed to deal with any bacterial nasties. By the way, thank you so much for taking time to help me!

 

[Olderfart]

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?

FWIW, your water source seems unlikely to be the issue to me. I do have my suspicions about the air domes though. They may be causing more of a back and forth exchange of solution between the tray and the medium than I would expect in their absence. If that is the case, I think it suggests that the ph in your medium may be at least as low as you are seeing in your tray, likely lower. Whether that is a problem or not I do not know, but if you run into nute issues, I would be suspicious that the low ph could be locking stuff out.

In the meantime, unless you see nute issues, I would be inclined to keep doing what you are doing.

Good luck with it.

 

[briefbriefs]

FWIW, your water source seems unlikely to be the issue to me. I do have my suspicions about the air domes though. They may be causing more of a back and forth exchange of solution between the tray and the medium than I would expect in their absence. If that is the case, I think it suggests that the ph in your medium may be at least as low as you are seeing in your tray, likely lower. Whether that is a problem or not I do not know, but if you run into nute issues, I would be suspicious that the low ph could be locking stuff out.

In the meantime, unless you see nute issues, I would be inclined to keep doing what you are doing.

Good luck with it.

Thank you! Yeah im in the home stretch for this grow. 20-25 more days left more or less....so im just praying that i can make it to harvest and then start again with the knowledge ive gained during this grow.

 

[briefbriefs]

FWIW, your water source seems unlikely to be the issue to me. I do have my suspicions about the air domes though. They may be causing more of a back and forth exchange of solution between the tray and the medium than I would expect in their absence. If that is the case, I think it suggests that the ph in your medium may be at least as low as you are seeing in your tray, likely lower. Whether that is a problem or not I do not know, but if you run into nute issues, I would be suspicious that the low ph could be locking stuff out.

In the meantime, unless you see nute issues, I would be inclined to keep doing what you are doing.

Good luck with it.

OF ive got a quick question for you -- do you have any experience with promix hp in autopots or know if thats something i can use in autopots? I was gifted a bag of promix hp and was thinking of mixing it with coco for my next run... 40% promix / 20% coco / 40% perlite. What do you think?

 

[Olderfart]

Thank you! Yeah im in the home stretch for this grow. 20-25 more days left more or less....so im just praying that i can make it to harvest and then start again with the knowledge ive gained during this grow.

Learning is one of the things that makes growing interesting and fun. Good luck with the rest of the grow. These plants are tough, so you should be fine if you stay on it. Lots of help here if issues come up.