Delps8
Well-Known Member
I've got a recent problem of the pH dropping. Most recent example is 5.9 to 5.3 in less than 18 hours.
Grow Equipment and Environment
Strain - AK-48
Number of Plants? 2
Growth Stage? Flower - week 1.6
How Long? 4 sets of nodes on 7/20/17
Indoor or Outdoor? Indoor
Grow Type - Hydro
Reservoir Size - 35 gals capacity, 28 gals to refill to 1/2" below net pot
Reservoir Temperature - 68 ±0 (Active Aqua chiller)
Medium - Started in rockwool
Hydro Setup - RDWC
Size (Wattage) of Light? How Many? 1 "600" watt LED, mfg says it draws 320 watts but KillaWatt reports 400.
Is it Air Cooled? Yes, cooled by internal fans.
Temperature of Room/Cabinet? Average high is 82±, average low is 72±.
RH - Average high about 72%, average low about 68%
PH - 5.8, has varied from 5.5 to 6.0
Pests - None known
Type and Strength of Fertilizers used? Fox Farm hydro nutes at about 60% recommended strength. Using the 420magazine.com "Wonder Chart" for analysis.
Size or Square Footage of Room? 2' x 4' x 8'
Using an EC + temp + pH monitor and really like it. Active Aqua water chiller is excellent for my needs. The RO unit feeds a 55 gallon cistern in the garage. The cistern temp is about 80 (August in Southern California) and the chiller brings the res down to 68 in < 6 hours.
Plants are growing very well. One is much taller than the other (note_ burn + the taller one is a beast) but both have lots of new growth that's a healthy green color.
Hydro unit has "top feed" function that runs 15 minutes every six hours.
Problem Statement
My grow is just getting into week 2 of flower and since flipping (or maybe a bit before that), my pH has been dropping every day. I'm not using any Down at all. It's all Up and 20+ ml at times.
Most recent example - fresh res yesterday, Ph'd to 5.9 at 1600. Checked plants this AM, and pH was 5.3. That's the biggest swing I've seen and it's never been below 5.5 before.
When I change the res, I don't sterilize it or clean it. I use a sump pump to empty the res and there's < 2 gallons remaining. No odors or visible dead things in the res.
I did a res change yesterday and filled the res with the mix for Fox Farms week 6 for hydro. Their chart calls for an EC of 1.6 - 1.8 but I'm using lower concentrations because based on conventional wisdom and I caused some nute burn. Right now the res is at 1.1/790 (0.7 factor).
The "wonder chart" (the chart the maps rising, static, falling for water, EC, and pH) indicates that I need a res change and to "lower EC if over 1.4, raise EC if lower than 1.0 so that's not much help since I'm at 1.1.
I did pull a dumbshit move and used the wrong conversion EC <== PPM factor. That caused some nute_ burn but that resolved a few days ago.
I've read here on 420 that a res that needs a large amount of Up may have root problems. The chiller keeps that res at a steady 68 and I add HydroGuard with a res change since it takes about 8 hours to get the water temp from 80 down to 68.
Roots are very light tan instead of pure white but there's no mal odor. The roots smell "fresh".
I think I've read one explanation for pH drops like this is that the plants are taking in nutes that result in cations or anions (I don't recall which one it was) being generated and causing a drop in pH. That makes it sound like a pH drop of 5.9 to 5.3 over night is acceptable. That just doesn't sound right to me.
Thoughts, advice, comments?
Grow Equipment and Environment
Strain - AK-48
Number of Plants? 2
Growth Stage? Flower - week 1.6
How Long? 4 sets of nodes on 7/20/17
Indoor or Outdoor? Indoor
Grow Type - Hydro
Reservoir Size - 35 gals capacity, 28 gals to refill to 1/2" below net pot
Reservoir Temperature - 68 ±0 (Active Aqua chiller)
Medium - Started in rockwool
Hydro Setup - RDWC
Size (Wattage) of Light? How Many? 1 "600" watt LED, mfg says it draws 320 watts but KillaWatt reports 400.
Is it Air Cooled? Yes, cooled by internal fans.
Temperature of Room/Cabinet? Average high is 82±, average low is 72±.
RH - Average high about 72%, average low about 68%
PH - 5.8, has varied from 5.5 to 6.0
Pests - None known
Type and Strength of Fertilizers used? Fox Farm hydro nutes at about 60% recommended strength. Using the 420magazine.com "Wonder Chart" for analysis.
Size or Square Footage of Room? 2' x 4' x 8'
Using an EC + temp + pH monitor and really like it. Active Aqua water chiller is excellent for my needs. The RO unit feeds a 55 gallon cistern in the garage. The cistern temp is about 80 (August in Southern California) and the chiller brings the res down to 68 in < 6 hours.
Plants are growing very well. One is much taller than the other (note_ burn + the taller one is a beast) but both have lots of new growth that's a healthy green color.
Hydro unit has "top feed" function that runs 15 minutes every six hours.
Problem Statement
My grow is just getting into week 2 of flower and since flipping (or maybe a bit before that), my pH has been dropping every day. I'm not using any Down at all. It's all Up and 20+ ml at times.
Most recent example - fresh res yesterday, Ph'd to 5.9 at 1600. Checked plants this AM, and pH was 5.3. That's the biggest swing I've seen and it's never been below 5.5 before.
When I change the res, I don't sterilize it or clean it. I use a sump pump to empty the res and there's < 2 gallons remaining. No odors or visible dead things in the res.
I did a res change yesterday and filled the res with the mix for Fox Farms week 6 for hydro. Their chart calls for an EC of 1.6 - 1.8 but I'm using lower concentrations because based on conventional wisdom and I caused some nute burn. Right now the res is at 1.1/790 (0.7 factor).
The "wonder chart" (the chart the maps rising, static, falling for water, EC, and pH) indicates that I need a res change and to "lower EC if over 1.4, raise EC if lower than 1.0 so that's not much help since I'm at 1.1.
I did pull a dumbshit move and used the wrong conversion EC <== PPM factor. That caused some nute_ burn but that resolved a few days ago.
I've read here on 420 that a res that needs a large amount of Up may have root problems. The chiller keeps that res at a steady 68 and I add HydroGuard with a res change since it takes about 8 hours to get the water temp from 80 down to 68.
Roots are very light tan instead of pure white but there's no mal odor. The roots smell "fresh".
I think I've read one explanation for pH drops like this is that the plants are taking in nutes that result in cations or anions (I don't recall which one it was) being generated and causing a drop in pH. That makes it sound like a pH drop of 5.9 to 5.3 over night is acceptable. That just doesn't sound right to me.
Thoughts, advice, comments?