pH problems, organic chem no help

[specklefart]

I’ve scoured the forums and haven’t been able to find a solution for my problem. I’m having trouble with pH rise despite always draining to waste. Invariably after pHing my nutrients to 5.8 the pH will rise to 6.1. I’ve checked a few hours later and it stable, but by 24 hours it is back up. If I correct with GH pH down, by the next day it is back to 6.1. The highest I have seen it creep is 6.3 after 4-5 days.

My starting tap water is extremely alkaline, pH around 10, ppm 150, so I use an RO. Water from the RO comes out about 30ppm, still pH 10.

I used GH flora and Botanicare Calmag throughout veg. Added calmag, then nutes which brings it down to about 6.5. From there I used pH down. Tried switching from GH to Mega Crop + calmag bc of all the hype on this site. I have had the same issues with pH rising.

Additionally my reservoir is a 15 gallon RV tank, mostly sealed other than around my lines. I only fill it about 5 gallons. It’s supposedly UV protected. I do keep an air stone in there and have tried taking it out with no success. I haven’t noticed any slimy buildup or odor. My water is about 63 degrees. I have been correcting my pH almost daily, but I’m concerned this could cause a phosphorus excess.

My plants are somewhat happy. Growing in Rockwool, switched to flower five days ago after defoliating. I’ve been correcting what I suspect is a magnesium deficiency. Noticed some nute burn as well with EC at 1.5. Feeding an hour after my lights turn on, every 1.5 hours for 9 hours with mild runoff. Temps around 22 during day and 19 at night. 22 at leaves. Humidity 50-60. Growing in a 4x2 under 320 watt HLG lights about 30 inches away. I don’t know if I need to test my water something that’s buffering it to around 6.1.

 

[MIMedGrower]

I’ve scoured the forums and haven’t been able to find a solution for my problem. I’m having trouble with pH rise despite always draining to waste. Invariably after pHing my nutrients to 5.8 the pH will rise to 6.1. I’ve checked a few hours later and it stable, but by 24 hours it is back up. If I correct with GH pH down, by the next day it is back to 6.1. The highest I have seen it creep is 6.3 after 4-5 days.

My starting tap water is extremely alkaline, pH around 10, ppm 150, so I use an RO. Water from the RO comes out about 30ppm, still pH 10.

I used GH flora and Botanicare Calmag throughout veg. Added calmag, then nutes which brings it down to about 6.5. From there I used pH down. Tried switching from GH to Mega Crop + calmag bc of all the hype on this site. I have had the same issues with pH rising.

Additionally my reservoir is a 15 gallon RV tank, mostly sealed other than around my lines. I only fill it about 5 gallons. It’s supposedly UV protected. I do keep an air stone in there and have tried taking it out with no success. I haven’t noticed any slimy buildup or odor. My water is about 63 degrees. I have been correcting my pH almost daily, but I’m concerned this could cause a phosphorus excess.

My plants are somewhat happy. Growing in Rockwool, switched to flower five days ago after defoliating. I’ve been correcting what I suspect is a magnesium deficiency. Noticed some nute burn as well with EC at 1.5. Feeding an hour after my lights turn on, every 1.5 hours for 9 hours with mild runoff. Temps around 22 during day and 19 at night. 22 at leaves. Humidity 50-60. Growing in a 4x2 under 320 watt HLG lights about 30 inches away. I don’t know if I need to test my water something that’s buffering it to around 6.1.

Looks like calcium spotting. Likely from too much. Maybe stop the cal mag. Plenty of calcium in the base nutes.

Also the high ph in the ro water doesnt matter. With low ppm ot will instantly take on the ph of whatever gets poured in or its poured on.

 

[Dirtbag]

I'd be suspect it's the water. And you are totally right, constantly adding ph down is not good. What happens if you ph it down to 5.5? Does it stil rise to 6.1 or does it settle lower? The plants can totally take it at 5.5, especially if it drifts up a bit and you'll actually get better N uptake. You could also maybe try a more acidic nutrient. I use pure blend pro and it's very acidic.

Also, how long have you been watering that frequently? Those short cycles arent allowing for much dryback. How do the roots look?

 

[specklefart]

I'd be suspect it's the water. And you are totally right, constantly adding ph down is not good. What happens if you ph it down to 5.5? Does it stil rise to 6.1 or does it settle lower? The plants can totally take it at 5.5, especially if it drifts up a bit and you'll actually get better N uptake. You could also maybe try a more acidic nutrient. I use pure blend pro and it's very acidic.

Also, how long have you been watering that frequently? Those short cycles arent allowing for much dryback. How do the roots look?

The lowest I’ve ever pH’d was to 5.6 and it was 6.0 the next day. Roots are white and healthy. When I switched to flower (Monday) I wasn’t getting any runoff at 3 hour intervals. I increased my feed a few seconds and still didn’t have runoff so I elected to add two feed intervals. I guess I should do less frequent, larger feeds to runoff??

 

[oldskol4evr]

i dont see how it is even possible for your water to be 10 and have 150 ppm ,just sounds wrong,that is damn near sewage water at that level,i suspected you need to check your meter until i seen plants,then you say 10 ph with 30 ppm ro water ,what scale are you on ,highest i ever seen ro water was a neutral 7. 0 with 5ppm ,explain that to me im clueless how you have plants at all at 10 ph,im new to this

 

[MIMedGrower]

i dont see how it is even possible for your water to be 10 and have 150 ppm ,just sounds wrong,that is damn near sewage water at that level,i suspected you need to check your meter until i seen plants,then you say 10 ph with 30 ppm ro water ,what scale are you on ,highest i ever seen ro water was a neutral 7. 0 with 5ppm ,explain that to me im clueless how you have plants at all at 10 ph,im new to this

I missed the 150 ppm. Mine is 150 at 8.0 but comes out in runoff of ocean forest at 6.5 with no adjustment. 150 ppm water is good usually.

I think you have something here. Ph meter calibration needed?

 

[oldskol4evr]

I missed the 150 ppm. Mine is 150 at 8.0 but comes out in runoff of ocean forest at 6.5 with no adjustment. 150 ppm water is good usually.

I think you have something here. Ph meter calibration needed?

at 8 i wil buy all day long,that is still a level for human consumtion,this crappy city wate ri had was right at 7.5 and 230 ppm and taste like shit,use to have to bubble the shit ,but the soil buffered it,since i moved and got this well water i dont know from one feed to the next what it is,we only use for baths ,laundry and toliets and such shit as that,all potable water is bought and it is ro water,7.0 ph 5 ppm and it taste like shit hahaha,i cant stand it,i take my meds with the well water it taste better to me,hadnt killed me yet but a 10.0 ph wut the hell

 

[Dirtbag]

The lowest I’ve ever pH’d was to 5.6 and it was 6.0 the next day. Roots are white and healthy. When I switched to flower (Monday) I wasn’t getting any runoff at 3 hour intervals. I increased my feed a few seconds and still didn’t have runoff so I elected to add two feed intervals. I guess I should do less frequent, larger feeds to runoff??

Depends how much rockwool they're in I think. I should say I dont really know a ton about different rockwool feeding schedules and I'm only on my first cycle with rockwool myself, I havent actually completed a full grow in it yet. And I know there is always differing opinions on things.

Most of what I've read though? is that with rockwool you want pretty good dryback in flower so air is drawn into the rootzone between feedings. In flower Im drying down to as low as 30-40% capacity overnight in my Hugo's, and then I irrigate to 80-90% capacity first feed at lights on, dryback to 40-50%, irrigate to saturation with a little runoff for the second watering, then dryback to 40-50% again, and irrigate to 15-20% or so runoff for the last feed of the day 3 hrs before lights out. Gotta have the feeding dialed though I've found lol. A little goes overboard quick. But that's just how I do things, I dont know enough about rockwool to say that what your doing is any better or worse than how I do it.

As for your ph issue, I'd just ph down it initially to 5.5 from the start and let it drift up to 5.9. Nothing wrong with that, and it's better than adding ph down constantly. A couple ph points off here or there isnt going to hurt the plant, It'll be happy between 5.6-6. But repeated applications of ph down to combat drift will eventually harm the plant.

 

[specklefart]

i dont see how it is even possible for your water to be 10 and have 150 ppm ,just sounds wrong,that is damn near sewage water at that level,i suspected you need to check your meter until i seen plants,then you say 10 ph with 30 ppm ro water ,what scale are you on ,highest i ever seen ro water was a neutral 7. 0 with 5ppm ,explain that to me im clueless how you have plants at all at 10 ph,im new to this

I was about to write my Mayor when I first got a tester, until I found out it is common knowledge. The water comes off the Missouri River so it is heavy in sediment. My pH and EC tester are both calibrated, I have the solution. They weren’t cheap either.

 

[specklefart]

Depends how much rockwool they're in I think. I should say I dont really know a ton about different rockwool feeding schedules and I'm only on my first cycle with rockwool myself, I havent actually completed a full grow in it yet. And I know there is always differing opinions on things.

Most of what I've read though? is that with rockwool you want pretty good dryback in flower so air is drawn into the rootzone between feedings. In flower Im drying down to as low as 30-40% capacity overnight in my Hugo's, and then I irrigate to 80-90% capacity first feed at lights on, dryback to 40-50%, irrigate to saturation with a little runoff for the second watering, then dryback to 40-50% again, and irrigate to 15-20% or so runoff for the last feed of the day 3 hrs before lights out. Gotta have the feeding dialed though I've found lol. A little goes overboard quick. But that's just how I do things, I dont know enough about rockwool to say that what your doing is any better or worse than how I do it.

As for your ph issue, I'd just ph down it initially to 5.5 from the start and let it drift up to 5.9. Nothing wrong with that, and it's better than adding ph down constantly. A couple ph points off here or there isnt going to hurt the plant, It'll be happy between 5.6-6. But repeated applications of ph down to combat drift will eventually harm the plant.

Your feed schedule makes logical sense. I’ve stared at this chart, but it looks like they’re recommending about 16 small feeds lol

 

[Dirtbag]

114ppm calcium carbonate in that water apparently. That explains things.

 

[oldskol4evr]

I was about to write my Mayor when I first got a tester, until I found out it is common knowledge. The water comes off the Missouri River so it is heavy in sediment. My pH and EC tester are both calibrated, I have the solution. They weren’t cheap either.

do you have to pay a water bill? thats freaking nut there

 

[Dirtbag]

Also notice your sodium is quite high at 56ppm. Probably from the city softening the water. Which means chloride content is also likely quite high. Chloride is no bueno for cannabis. Should be fine after passing through your RO filter though.

 

[specklefart]

114ppm calcium carbonate in that water apparently. That explains things.

Also notice your sodium is quite high at 56ppm. Probably from the city softening the water. Which means chloride content is also likely quite high. Chloride is no bueno for cannabis. Should be fine after passing through your RO filter though.

Yeah man. Actually I misinformed you earlier, just tested for the first time in months and it comes in at 0.6 EC or 274 ppm. I got the RO bc I wanted to try to have a blank slate.

 

[specklefart]

do you have to pay a water bill? thats freaking nut there

I pay for waste and storm water as well. It is the only city with completely free public transportation though, which I’m happy to help people with.

 

[Beachwalker]

My city tap water is 8.9 at 95 PPM. I don't know what's causing your rise but I know that the new megacrop as mentioned above does not need Cal/Mag supplementation like the original formula did, I'm assuming you have the new formula? Good luck

 

[specklefart]

Looks like calcium spotting. Likely from too much. Maybe stop the cal mag. Plenty of calcium in the base nutes.

Also the high ph in the ro water doesnt matter. With low ppm ot will instantly take on the ph of whatever gets poured in or its poured on.

Update: Plants are doing well since I stopped adding Cal-Mag. All new growth is very healthy.

I’ve been ph’ing to 5.5 and it takes a few days before drifting to 6.1.

Thanks for the advice.

 

[specklefart]

Overall I feel like things are going well. I suspect I’m getting a little nitrogen toxicity in my lower canopy. I’m curious if other people have seen that with the N in Megacrop during flower. EC is at 1.5. I think my buds are appropriate for 3 weeks into flower.

 

[Matthewstever]

Get rid of the GH pH down. I had the same issue with it. pH drifted up constantly.
Now I use good ole sulpheric acid for pH down when I need it...my pH stays stable for a few days at a time now..

 

[specklefart]

4 weeks into flower.