Running promix hp with liquid fertilizers. Only feed/ water when the pot feels light. The feed is 2.3 ec at 6.2 ph (according to manufacturer specs). When i feed/water i water until a decent amount of runoff. The runoff ph is 5.6ph so the promix hp is lowering the ph of the feed water as it sits in the pot for the 2 ish days until next watering. This is causing some slight deficiencies. Should i bump the feed water to like 6.6ph so it can drop to the correct range of around 6ish while it sits in the promix inside the pot for the 2 days?
⚠️PH Problems in ProMix HP ⚠️
- Thread starter RCJR
- Start date
Herb & Suds
Well-Known Member
I leave my base water at 8.1ph
The nutrients lower it but I don’t even measure it or runoff
No issues
The nutrients lower it but I don’t even measure it or runoff
No issues
With synthetic nutrients?
Herb & Suds
Well-Known Member
I run jacks 321
J2M3S
Well-Known Member
I also stopped PH the water also. Using MegaCrop.
And after you add the nutes to the water the ph is 8.1?
xox
Well-Known Member
i use promix with advanced nutrients after mixing the nutrients in the water my feed is at 6.1 ph however the thing is the ph of your feed doesnt matter much its the ph of the medium that maters. the thing about peat is its inherently acidic to counter this they add dolomite lime to buffer the mediums ph. the thing about dolomite lime is, it gets used up so to speak. if your having problems with ph with promix the most likely problem is your ph is too low because theres not enough dolomite lime in your medium to remedy this you could sprinkle a couple table spoons ontop of your medium and water it in with your next watering that should remedy your problem. id stop checking the run offs ph thats not a good indicator of whats going on its better to use a soil ph probe.
Do you ever check your runoff ec? Mine is always high in promix hp but hasn't affected my plants until I've been hand watering and letting the media dry back before watering again (ruffly 2 to 3 days in 10 gallon pots) (when i say watering i mean feed and water, they only get regular tap the last week of flower)
xox
Well-Known Member
theres lots of different brands of soil probes bluelabs is a good brand can get them on amazon, no i dont check my run off. never check run off its not an accurate measurement. i dont water until run off. i just water them a bit every few days. i also add an extra cup of dolomite lime to every 5 gallons of promix tend to run into less issues when i put the plants into there final pots. ever since i started doing that i havent even had to use any instruments to check anything smooth sailing.
green_machine_two9er
Well-Known Member
What’s the whole plant look like?
OldMedUser
Well-Known Member
How many other leaves look like that? It doesn't look wide-spread like it should if it were a deficiency/excess problem or caused by pH issues.
Pretty high feed level so I'd suspect overfeeding to be your issue if anything.
Pretty high feed level so I'd suspect overfeeding to be your issue if anything.
OldMedUser
Well-Known Member
I've used HP for almost 20 years mainly with AN 3-part and RO water so don't have to bother with pH but rarely feed higher than 1.2 EC every 2nd watering. I let the pots get quite light before giving a good soaking with rarely any runoff to take out of the trays. Like @xox says runoff pH is very inaccurate as is getting the pH of the media. I don't add any lime to mine and never see any issues I could relate to pH.
Im just going off the manufacturer grow guide and it says 2.3 ec (jr peters). I could lower my feed strength and see what happens.I've used HP for almost 20 years mainly with AN 3-part and RO water so don't have to bother with pH but rarely feed higher than 1.2 EC every 2nd watering. I let the pots get quite light before giving a good soaking with rarely any runoff to take out of the trays. Like @xox says runoff pH is very inaccurate as is getting the pH of the media. I don't add any lime to mine and never see any issues I could relate to pH.
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@OldMedUser @xox
So this is what I'll be doing with my Promix HP;
Using jacks RO formula 12-4-16 (with Epsom) ph to 6 to 6.3 at 1.8 ec (its recommended 2.3 ec but I'm lowering it)
Feed watering only when the pot feels dry (by lifting the pot)
Feed watering enough to saturate but NO run off
Check the ph with a soil probe inside the pot now and again to make sure its around 6. If too low add a little dolomite lime (top dress) then check ph in the pot a week or so later.
Sound good? Am i forgetting anything?
So this is what I'll be doing with my Promix HP;
Using jacks RO formula 12-4-16 (with Epsom) ph to 6 to 6.3 at 1.8 ec (its recommended 2.3 ec but I'm lowering it)
Feed watering only when the pot feels dry (by lifting the pot)
Feed watering enough to saturate but NO run off
Check the ph with a soil probe inside the pot now and again to make sure its around 6. If too low add a little dolomite lime (top dress) then check ph in the pot a week or so later.
Sound good? Am i forgetting anything?
xox
Well-Known Member
that sounds like a good start good luck
OldMedUser
Well-Known Member
I wouldn't bother using the soil probe to check pH as they are inaccurate as hell. Jacks is basically just hydro nutes and should be fine at whatever pH it happens to be. If anything I think your plants are showing signs of nutrient buildup in the leaves and will likely be going all brown, thick feeling and crispy over the coming weeks. If so there's nothing you can really do about that as the damage is already done.
What is your general humidity like in the grow area? With lower RH EC should also be lower to prevent toxic salts buildup over time. Mine is chronically low so I feed half or less what the nutes instructions are. The levels any nute maker quotes on their containers is just a suggestion for the max to use. Generally half the max is best to go with unless signs of not enough show in the plants with yellowing older fan leaves. 'Tis better to have to add more than try to reduce levels in your pots tho having lots of runoff to lower levels can fix an excess feed problem early in the grow.
Usually toxic salts buildup will start in older fan leaves and work up but if upper leaf temps are elevated by intense lighting more water is transpired thru those causing more rapid salts buildup until the leaves begin to fry from the inside out.
I'm hoping that's not your issue but really suspect it is.
Fingers crossed!
@OldMedUser if it is nutrient build up how would i fix that. A big medium flush would flush out the lime in the promix hp correct?
I can't get my humidity below 50% in flower
I can't get my humidity below 50% in flower
OldMedUser
Well-Known Member
Not really as the two types of lime in HP are slow release so it's mostly easily dissolved nutrient salts that are flushed out. I've tried that with my plants in the past and it really didn't help. I saturated the pots with RO water first then let that sit for an hour or so so stuff could dissolve into it then poured enough 1/4 strength nutes thru to push all that out as runoff. About 1gal in a 4gal pot was enough. This was about midway thru flowering when the leaves started frying en-mass. Ended up with even the little bud leaves going all toasty brown by harvest time. It took me a few grows to figure out wtf was going on. In mid winter my RH can be down around 25% or even less so I've always meant to run a sealed room system but never did. As long as I feed low it doesn't cause problems.
50% during flower is fine. Over 60 is where you can run into problems like bud rot near the end tho with good air circulation around the plants it usually won't show up.