Promix HP and pH

[DaveL]

Hi all.
I'm using Promix HP and would like to know the proper ph of the feed. Its native ph is around 5.8 I believe but feeding in the high 5's has resulted in cal/mag issues late in flower. Upping my ph to 6.3 to 6.5 has definitely helped but what should I be aiming for. I do add cal/mag every watering/feeding. Using LED lighting.
Any info on proper ph using this medium would be greatly appreciated.

 

[fanleaf]

5.8ish is where you want to be in Promix. It's as hydro. You can swing from 5.6-6.0 but 6.3 is more for soil than promix. There are many factors that can cause a calcium or magnesium issue other than pH. If you are a little hot on certain nutes it can make it harder for the plant to absorb calcium and magnesium. Temperatures in the room also have great effect.

 

[farside05]

I've been pHing to 6.2 - 6.4 in Pro Mix for years. I figure it's balanced to 5.8 so I feed on the higher side and let the media drag it down through the range.

 

[fanleaf]

5.8-6 for several years here. Works great for me

 

[farside05]

@InTheShed Has a pretty interesting thread going on over HERE re: his recent conversations with the makers of Pro-Mix.

 

[DaveL]

Thanks for the responses folks. I was ph ing to 5.8-6.0 for most of the grow and all was good. I'm now approaching 10 weeks flower (White Widow). I fully expect some leaf issues late in flower but this very much looked like cal/mag deficit. Upping the ph stopped the progression.
My understanding is to treat Promix similar to hydro as it is soiless but doesn't the ph need to be above 6.1 for the uptake of calcium/magnesium? None of this is terribly important this grow as it is just about finished but the next grow is right around the corner.
I'm pretty new at growing but have had respectable results with Promix. 2 WW auto's produced almost 5 ounces dry and I have 4 WW photo period finishing now. I expext 2-3 ounces per.

 

[farside05]

Thanks for the responses folks. I was ph ing to 5.8-6.0 for most of the grow and all was good. I'm now approaching 10 weeks flower (White Widow). I fully expect some leaf issues late in flower but this very much looked like cal/mag deficit. Upping the ph stopped the progression.
My understanding is to treat Promix similar to hydro as it is soiless but doesn't the ph need to be above 6.1 for the uptake of calcium/magnesium? None of this is terribly important this grow as it is just about finished but the next grow is right around the corner.
I'm pretty new at growing but have had respectable results with Promix. 2 WW auto's produced almost 5 ounces dry and I have 4 WW photo period finishing now. I expext 2-3 ounces per.

The thread I linked has more info. The Pro Mix guy is less concerned about the pH going in and more about the pH of the substrate. That can be influenced by a number of things, the nutes you are using and their chemical makeup, the akalinity of your water, etc. I say, if raising it seemed to solve your problem, keep doing it that way.

 

[Elvin]

The thread I linked has more info. The Pro Mix guy is less concerned about the pH going in and more about the pH of the substrate. That can be influenced by a number of things, the nutes you are using and their chemical makeup, the akalinity of your water, etc.

Perhaps it's because I've grown up around commercial grain growing operations, but what the Pro-Mix guy is sharing is not all that revelationary, in fact, it is how the 1000+ acre operations operate; you keep an eye on your soil's condition by knowing what your inputs will do to that soil, and that soil's condition directly relates to nutrient uptake (too much accumulates and it changes the substrate).

 

[DaveL]

Thanks Farside05. I actually did check out the article. As you mentioned, if it works for me, keep on keeping on.