⚠️PH Problems in ProMix HP ⚠️

OldMedUser said:

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.

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I thought you didn't feed until runoff because of the risk of flushing the lime out of the promix hp?

RCJR said:

I thought you didn't feed until runoff because of the risk of flushing the lime out of the promix hp?

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Not at all. I never bothered getting runoff as I fed low enough that salts didn't build up in my medium enough to warrant flushing any out. If I did get some runoff it was usually because I watered too fast and if left for a while it would be sucked back up into the pots. I always measure the amount of water it takes to saturate a pot then feed 10% less so I can just pour in that amount and let the tray fill up to be drawn back in. If there's any left in the trays an hour later then I remove that with a hand towel I keep in the grow room just for that purpose. Rarely had to remove any tho.

Dolomitic lime will maintain a pH of around 7 which is a little too high as growing in HP with hydro nutes a pH of 6 or even lower is a better range. I did DWC for a lot of years before switching to all in HP just a few years ago and kept pH in DWC to 5.5 but it would rise to about 6.2 every 3 days. Sometimes it would be down to 5 after knocking it back with conc sulphuric acid but would go back to 6+ in 3 days. I use the same AN nutes in HP so don't bother with pH and didn't once I made the switch in DWC to the pH Perfect type of AN 3-part.

Tap water also adds mineral salts to the load but I've always used RO or distilled water only as mu tap water comes from a dugout on my property and is pH 8+ and around 400ppm depending on season.

I'm a new grower using Promix UP, maybe someone can help here:

I'm using Maxigrow/Maxibloom with soft tap water (<100 ppm) so I've been treating it like RO water. I supplement with about 200 ppm of cal mag every watering but it seems every grow I get the red streaking on the stems and branches. I know that my base nutrients contain some calcium and magnesium also so I'm not sure where I'm falling short.... Or maybe I'm overdoing it?

I'm using an LED light providing around 700 par at the canopy with good temps and air flow/exchange

On day 11 since flip to 12/12 so I decided to get at least one foliar spraying of magnesium before the bud sites start to form.

Current Water/Feed Routine and Stats:

Input ph 5.8, Input ppm around 800
Output ph: 6.1, Output ppm around 1200

Feed 200 ppm Cal Mag, 600ppm MaxiGrow/Maxibloom

Watered until around 10-20 percent runoff

Here's a few pics of the plants and some crappy looking clones I took, HA!

(Chem '91 x Chem D)



Thanks for any help, advice, suggestions, and/or good natured ribbing

TankHankerous said:

soft tap water (<100 ppm) so I've been treating it like RO water.

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As in water thats been run through a salt based water softener??
Man you are asking for trouble using that.
Salt build ups, improper uptake because the plant thinks it got more water than it did thanks to the salt.

Might want to install a tap before your softener so you can get fresh tap water.
Other options are, youll have to go RO or fresh spring water.

leatherbackturtle420 said:

As in water thats been run through a salt based water softener??
Man you are asking for trouble using that.
Salt build ups, improper uptake because the plant thinks it got more water than it did thanks to the salt.

Might want to install a tap before your softener so you can get fresh tap water.
Other options are, youll have to go RO or fresh spring water.

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I'm not sure how it's treated. It's NYC tap water out of the faucet but don't know if they run it through a sodium based softener.

PH is between 7 and 8 and when I use my ppm pen no numbers show so that means its less than 100 ppm

TankHankerous said:

I'm not sure if it's run through a softener. It's NYC tap water out of the faucet but don't know how it's treated. PH is between 7 and 8 and when I use my ppm pen no numbers show so that means its less than 100 ppm

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Should just be chlorinated water. As an upstate New Yorker, i dont see NYC spending the kind of cash on a city wide water softening system lol.
Go ahead and use the tap.