My runoff pH suddenly decreased

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Mugwort

Mugwort

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In the past week the pH of my runoff has plummeted. She’s in her sixth week of flower. I monitor it pretty closely and I haven’t had any problem keeping the pH above 6. A few days ago it was 5.5. I’ve titrated my nute solution to around 7.3 and it’s still decreasing and was down to 5. How can this be when nute/H2O solution is on the basic side and pH is still decreasing. I’m new at this but I figure this is a pretty critical point in bud development. Do I need to get aggressive or should I adjust feeding pH like I have been and wait. pH was measured using a meter and one of those test kits solutions too.
 
TripsRabbit

TripsRabbit

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Is there a problem?
Why are you measuring runoff ph?
 
mysticepipedon

mysticepipedon

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In the past week the pH of my runoff has plummeted. She’s in her sixth week of flower. I monitor it pretty closely and I haven’t had any problem keeping the pH above 6. A few days ago it was 5.5. I’ve titrated my nute solution to around 7.3 and it’s still decreasing and was down to 5. How can this be when nute/H2O solution is on the basic side and pH is still decreasing. I’m new at this but I figure this is a pretty critical point in bud development. Do I need to get aggressive or should I adjust feeding pH like I have been and wait. pH was measured using a meter and one of those test kits solutions too.
Soil has what is called buffer capacity. This is from two sources:

1. undissolved solids, like crushed limestone, dolomite, gypsum, phosphates, etc.
2. positively charged ions being held by the soil's cation exchange sites.

This buffer capacity is the main thing that makes growing in soil different from soilless cultures. Yours is dominated by cations that maintain the pH in a low range. This can include hydrogen, iron, aluminum and some other metals. When your high pH water runs through, the soil buffers the pH change with "reserve acidity."

Water has NO buffer capacity, so its pH can change instantly. It has a tough time fighting the buffer capacity of a peat-based soil (or most natural soils containing clay and organic matter).

How large are your pots? How much soil are we dealing with?

Well into flower, your options include adding some crushed limestone to the surface and mixing limestone with your water, next time you water. (Dolomite is fine too — I prefer it.)

When mixing with water, it will not dissolve (or really, it dissolves slightly, but you won't notice), so what you want to do is make sure the limestone is crushed to a powder as best you can. The object here is to get some fine particulate lime to work its way deep into your soil. Keep the water cloudy, don't let it settle.

Do this each time you water until the situation improves.

.
 
Mugwort

Mugwort

302
63
I appreciate the explanation. I know pH is an logarithmic expression of the concentation of H+ ions. I am using a pH meter and slightly buffering feeding solutions to around 7.3. I am having trouble getting the runoff above 5.6. I am in my 6th/7th week of flower phase and bud growth has seem to slow and signs of nute lockout are showing. Got to get the pH up quick.
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TripsRabbit

TripsRabbit

1,259
163
I looks almost like spider mites, have you scoped the bottoms of the spotted fan leaves for buggies?
 
TripsRabbit

TripsRabbit

1,259
163
Treatment every 3 days for at least 3 treatments preferably 4 treatments, 2 treatments of each. Depending on how strong you mix it and how bad it damages your plants.
 
TripsRabbit

TripsRabbit

1,259
163
You can wrap your stalks in saran wrap and paint it with tanglefoot sticky trap.
Spray the whole room down with green cleaner, spray yourself with it, spray the dog with it. It's just soybean oil and alcohol.
 

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