BCrocker
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BCrocker said:Friend has a DWC setup and he just can't keep the PH up.. it keeps falling no matter what he does. What does this mean generally? Meter has been calibrated and tested another meter as well.
green punk said:A ph that continues to drop indicates something biological (in a bad way) occurring in the system. Root rot is usually first on the list to look for, then pests.
kamdavs said:If it is dropping daily you got root rot.
^^ These comments are wrong.
The osmotic processes of nutrient/mineral/waste exchange between the roots and the rez is very complex. As roots exchange salts and sugars and what-not, the pH will absolutely swing - sometimes wildly depending on what additives a grower has added and whether or not you have a sterile or living rez.
Perhaps a grower is using a bloom-boost with asorbic acid? Maybe there is a few ml/gallon of molasses? How about silica? What application rate for beneficials? What kind of oxygenation is provided to the system? Is it tap or RO water? Is the cal-mag package calcium nitrate or calcium carbonate?
Anyway - drawing those definite conclusions from the bare-bones information the OP provided is kinda sloppy.
We have no idea why the pH is dropping.
^^ These comments are wrong.
The osmotic processes of nutrient/mineral/waste exchange between the roots and the rez is very complex. As roots exchange salts and sugars and what-not, the pH will absolutely swing - sometimes wildly depending on what additives a grower has added and whether or not you have a sterile or living rez.
Perhaps a grower is using a bloom-boost with asorbic acid? Maybe there is a few ml/gallon of molasses? How about silica? What application rate for beneficials? What kind of oxygenation is provided to the system? Is it tap or RO water? Is the cal-mag package calcium nitrate or calcium carbonate?
Anyway - drawing those definite conclusions from the bare-bones information the OP provided is kinda sloppy.
We have no idea why the pH is dropping.
green punk said:A healthy ph swing might be from 5.5 up to 6.3. Anything beyond that is sloppy. IME .
green punk said:the conclusion is based on that the initial post states no matter what he does the ph drops. Which indicates biological processes not necessarily good ones occurring. Pretty basic stuff there.
green punk said:not sure about the osmotic processes and what have you
green punk said:I m not trying to have a pissing match here. It seems you really like to beat your drum and put others down rather than just stick to the the threads initial scope.
I run an AeroFlo2. When I overload the bennies, the pH drops like a stone. I don't get any visible slime, but I assume there are unwanted bacteria somewhere. Well, unless it gets bad.
You won't recover from this unless you totally clean the bacteria (in tubing, in media, old roots, ect). However, I have harvested while enduring this problem since late in veg.
hm, so the only possible reason for ph drop is unwanted bacteria?
Effects of Low Alkalinity
Not everybody in North America has irrigation water with high alkalinity. The primary problem associated with low alkalinity water is a tendency for media pH to drop over time. Growers often run into low pH problems when low water alkalinity is combined with a fertilizer high in ammoniacal nitrogen. Fertilizers high in ammoniacal nitrogen are acidic, and without any alkalinity in the water to balance the reaction (resist lowering of pH), acidic fertilizers will tend to drive the media pH down over time.
Fertilizers that are high in nitrate nitrogen often do not cause the media pH to increase when combined with low-alkalinity water. In fact, it is often recommended that growers with low alkalinity water use fertilizers high in nitrate nitrogen simply to maintain a stable media pH. When low media pH does occur in conjunction with a low-alkalinity water source, raising media pH with high-nitrate fertilizers may be difficult or impossible. Growers with low alkalinity should stock potassium bicarbonate or liquid lime, which raise media pH.
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