Pro Mix, Optimal pH, Chem ferts?

[Row]

OK so this is something that has been really playing on my mind for a while and i just cant not get a definitive answer.

Yes i can search and yes there are a couple of threads talking about pro mix and pH, but there are basically 2 different schools of thought. And they also are not distinguishing between using organic ferts and purely Chem ferts, in this case GH 3 part.

So my question is simple what pH is the perfect pH for promix and purly Chem ferts.

Some people say 6.2-6.5 like a soil ph

But isnt promix with chem ferts soilless? and in that case uses a more hydro pH of 5.2-5.8

Yet i also see people agreeing that it is soilless and not the same as soil and therefore not a 6.2-6.5 ph but a pH of 6.0 being optimal, but this ph is not optimal for soil or hydro argh.

I used to run a pH of 6.0-6.5 changing as the weeks went on to allow all elements to be available.

I have just recently used a ph of 6.0 all the way through but raised it at the end to 6.3.

It seems to me that they stayed more green at the 6.0 pH, but im not sure if this was just that N was more available or the whole spectrum and 6.0 is just a better ph? or just a million other factors.

I know that Mynamestitch recommends a ph of 5.8 if i recall correctly, now this is the ph that makes most sense to me, a hydro ph, but i still dont understand why if its a hydro ph it wouldn't be the whole 5.2 - 5.8 pH. But then other respected growers like REZDOG and Crazy composer both say 6.0.


I am presuming it is to do with the CEC of the soilless mix, so soil has a high CEC, so a 6.2-6.5 pH

Hydro a CEC of 0 so a 5.2-5.8 ph

And then something like Promix a CEC of 80 if i recall correctly, so this puts it in between the hydro and soil CEC's, so therefore the pH is in between the two at about 6.0. Note what i have just said about CEC and ph could be completely barking up the wrong tree so if it is, please correct me.


So please if anyone can really enlighten me as to what the optimal pH for a SOILLESS pro mix with purely chem ferts is and maybe even give some good reasoning and theory behind there answer that would be awesome and a huge weight off my mind.

Row

 

[10k]

I'll just say it as I know it will be challenged by others real soon.
A soil less mix should run the same as a hydro pH if you're running a chem nute system like GH flora series. So, without going into the many ways growers seriously damage their nute solution just in the mixing and pH adjusting process, or worse yet the flawed methods many growers use for add backs or topping maintenance of their chem nute reservoirs which cause serious damage to their nute solutions, arrrgh ! Trying to set and hold that current mindset of a solid 5.8 pH really needs rethinking imho.

My argument is that a 5.1 to 5.9 range is much more accurate with 5.2 being optimal, and I don't want to see that damn square bar pH chart I've been seeing lately around here in this discussion as it's completely full of shit as far as representing element availability in hydro correctly. I'll try to find a proper hydro pH chart and post it if I can, but the square bar style bar chart currently going around icmag is false information poorly representing nute availability in hydro and to be avoided.

A lot of folks have been preaching 5.8 as optimal start pH in hydro, but this imnsho is waaaayy wrong and a bad practice in hydro. Chem nute pH in hydro usually always drifts upwards. Setting a target start pH of 5.8 will cheat the plants out of seeing a fuller spectrum of availability and endanger them of more elements precipitating out or becoming unavailable when they're drifting upwards into the 6.5 range.
At 6.4 alot of elements become largely unavailable, above 6.5 and things really start to go haywire.

Here's an excerpt from flairform on why a 5.0 to 6.0 pH range is the right way to go in chem hydro...

It is over this pH range that all growth factors produce optimal growth. If the pH is allowed to rise much above 6.0, more than half the essential nutrient species (especially calcium, sulfate, and the trace elements copper, iron, manganese, and zinc) can precipitate, thus becoming immobile and unavailable for transport by the water flow to the roots. The precise pH at which precipitation of macronutrients starts is determined by the combined concentrations of calcium and sulfate. Except for fertilizers low in calcium and sulfate, this problem commonly occurs at pH values of around 6.5

Here's a growfaq excerpt...

The pH of the nutrient solution is a major determinant of nutrient uptake by the plant. If the pH wanders outside the optimum range of between pH 5.1 and pH 5.9, then nutritional deficiency and/or toxicity problems can occur. For hydroponic nutrient solutions used with inert media, keep the pH at 5.2 for optimal elemental uptake. It is at this point that roots most readily assimilate nutrients. These pH and TDS/EC recommendations may seem low relative to the normally suggested range, but are based upon information garnered from "Hydroponic Nutrients" by M. Edward Muckle and Practical Hydroponics and Greenhouses. They both document the low pH resulting in increased nutrient uptake and my experience has shown discernible health and yield improvements at a ph of 5.2 over higher levels.

On page 100, Hydroponic Nutrients displays both the assimilation chart for organic soil applications and another for inert medium hydroponics, which depicts the vastly different scenarios. The widely accepted soil based chart is frequently misapplied to water culture applications. His research and that done by others, documented in Practical Hydroponics and Greenhouses, indicate that iron and phosphorous precipitate in nutrient solutions at pH levels above 6. Stay below a pH of 6 by all means to avoid this problem and benefit.

 

[Row]

Hey 10K

Thx for the quick reply, and i totally agree on the whole letting the ph swing in hydro, from 5.1-5.9.

Are you also saying that i should follow this exact hydro ph and this swing in my Pro mix, i water only twice a week as im in soil beds,

I could start at week 1 with 5.1 and raise it by .2 over each week

week 1, Ph 5.1 5.2
Week 2 pH 5.3 5.4
Week 3 pH 5.5 5.6
Week 4 pH 5.7 5.8
Week 5 pH 5.9 5.8
Week 6 pH 5.7 5.6
Week 7 ph 5.5 5.4
Week 8 ph 5.3 5.2
Week 9 ph 5.3 5.4

So each water/feed changes the ph by 0.1 as not to stress the plants with a large jump.

If i new better what elements were available at different ph's i could instead of just going up and back down have the more nitrogen available ph at the start and a more phosphorous ph available at the end etc.

Or should i pic a mid way ph, or the optimum which you are saying is 5.2? as the promix has lime in it so the pH will rise as the medium dries giving the swing.

I have a much better ph chart from a book called, How to super charge your garden, but no scanner to scan it and post it, but i will also try and find a pic of it on the net.

Row

 

[guest 77721]

 

[Row]

Thats the one in the book redgreenry, thx

Sooo, is the left hand one or the right hand one

To me it makes sense that id be using the right hand hydro soilless one, however it just goes against what most people have told me and why im having a hard time watering my promix with a 5.2 ph water and feed.....

Any one out there using this low a ph in promix or similar with just chem ferts?

Row

 

[Row]

argh

Just read this on the Dutch masters web site

http://www.dutchmaster.com.au/?language=english&page=growers_guide&topic=soil_growers

SOILESS MIXES ( PROMIX/SUNSHINE MIX ):
These mixes, often referred to as soil mixes by many growers, are in fact soilless mixes composed mainly of sphagnum and peat mosses. These components are relatively inert and hold good amounts of air and moisture making them suitable as a good plant growth medium. In many ways these mixes are similar to hydroponic growing in Coco Coir. However these “soil” mixes often contain other components designed to release nutrients to the plants over time to try and provide a more “soil like” feel to them.

pH:
Remember in “soilless mixes you need to run the pH a little higher than you do in Hydro to allow full availability of all elements. The pH you need to use is pH 5.8 to 6.5.


So much contradictory information on this important and simple fact its driving me insane,

Seriously i think the only way im going to get to the bottom of this is to water a bunch of pots in the room with different ph levels and see which do better, please someone save me from that by having the definitive answer

Row

 

[guest 77721]

It's my experience running Promix with cheap chem nutes - Shultz 10-15-10 that problems would start when the pH dropped below 6.2. Adding D-Lime and maintaining the pH 6.5-6.8 with better nutes gives me good results. So I'm doing a soil style grow currently with AN nutes.

I think if you want to run Hydro style with low pH, you will have a running battle with the D-Lime as it buffers the pH and will pull it up over time. Promix is a blend of peat moss, vermiculite and perlite with some D-Lime. You could mix your own or try a perlite/vermiculite blend or go to CoCo.

 

[Oldmac]

argh
So much contradictory information on this important and simple fact its driving me insane,

Seriously i think the only way im going to get to the bottom of this is to water a bunch of pots in the room with different ph levels and see which do better, please someone save me from that by having the definitive answer
Row

Hey Row,

Your thread caught my eye because I have recently gone back to using pro-mix in a grow op I'm partnered in. Using it because my partner was a "dirt farmer" and is more comfortable with it.

Not sure this is a definitive answer ('cuase I'm sure some won't agree) but many years ago when I was using Pro-Mix and having a problem with hydro's low PH levels; I simply went to a couple of commercial greenhouse growers (ornamentals & vegtables) and asked them. ALL said Pro-Mix liked a PH abt 6 +/-.2 and that is what I starting doing. No problems after that.

That is what we use today, a PH of 5.8-6.2

BTW: greenhouse growers or distributors are a great source for pro-mix, nutrients, fish emulsion, plastic pots etc, at cheap prices. Most will sell to you, especially on a cash basis. They are also a great resource for info.

 

[ThaMagnificent]

Pro Mix is pretty simple to grow in tooo....I just had a run on Botanicare nutes and I rarely ever checked the pH....

 

[Row]

Hey guys thx for the advice,

I to have had many successful grows in promix but successful and perfect are different stories, untill i get 2lb + every go i am not doing as well as i could, currently i get 1.5-1.8

I know my environment is absolutely perfect, sealed room co2, perfect Day,Night temps and humidity with almost no swings, dialed in to the nines.

so to me the problem is one of feed/pH and i have seen so much contradiction on the matter it struck me as being something i needed a concrete answer on.

I will say this from the looks of my round that is in week 8 at the moment they seem to have liked me keeping the pH closer to 6.0 that going all the way up to 6.5, i doubt it will be more than 1.5 lb per light still, but that is due to other problems and the fact this is the first run in this place, had crap plants going in and way to few plus other problems.

I am starting to lean towards the pH olmac is using, i like that you got that information from a tried and tested source, do you know if they were using chem ferts or organic?

I however still dont get that on no chart iv ever seen is a pH of 5.8-6.2 optimal for soil or hydro........ argh

Row

 

[Oldmac]

yo Row,

The only glass house operator I know in my area doing real organics, is not using pro-mix.
They mix up thier own medium, sterilize it then add amendents that are "live" (like microbes). They devote one house (abt 1/3 acre) exclusively to organics, for the certification process.

Not sure about charts, but I'll take your word for it. Never really thought too much abt looking at a chart, once I tried 6.

 

[10k]

Yes...THAT's the better pH chart Red !

And this is a good discussion / debate topic.

Keep in mind that I'm talking about chem hydro nutes, taking into account that the solution pH will drift within a soil less medium very similar to the pH drift experienced within a recirculating hydro reservoir. I see everyones point about promix being more like a soil medium than a hydro inert medium like lavarock, lecastone, rw or even coco. But throw in the 20 to 30% perlite most folks use and it's suddenly closer to being a high drain inert soil less medium.

Yes, the added dol lime helps buffer the pH from going too low, but in that it's usually sending the pH upward within the medium giving the roots exposure to that drift in pH range. Until the lime is exhausted in the medium, the higher the pH going in will cause the higher pH drift in the medium, which will be a tad higher than what is seen in runoff pH. Or said another way, if it goes in at a solid 5.8 it's more likely to run off closer to the levels where chem hydro elements become much less available. In some ways, if a soil pH test is run the pH found is even higher than what's being seen in the run-off. Later in flowering when the plants are taking in more P than N, that drift may head the other direction, but most growers end up "treating" that by watering in more lime, turning the drift back around and upwards yet again.

Why should the grower chop in half the availability range by setting the initial pH at in the middle or near the top end of the usable range with a start at 5.8, thus letting the pH swing towards what is a danger zone if he's using a chem hydro nute package ?

Getting off more toward a chem nute solution in recirculating hydro purist thought wave..
Not much emphasis is put on Plant nutrition by "mass balance". Mass balance speaks to the fact that plants uptake different elements from the chem solution in hydro at different amounts and differing speeds, leaving behind or taking up more slowly or at lesser levels other elements on their dinner plates. Metaphorically speaking, if you give a child a daily dinner plate with several items on it...say a double quarter pound cheese burger, veggies and a big piece of chocolate cake...chances are he's going to slam down that cake first, then the cheese burger and not touch the veggies. If however, that plate has a smaller cheese burger, smaller piece of cake and the veggies...chances are alot better for him to eat everything on the plate.... Now look at the pH chart for hydro or soil less mediums and draw a line straight up from the 5.8 area to the magnesium and it becomes more clear why so many growers see mag and various other micronute and even P & K defs.

My point (very much up for discussion btw) is that...
Hydro and soil less mediums are certainly NOT flat line like the soil pH chart shows and don't buffer anywhere near the same as soils.
Chem nute packages are very prone to elements percipitating in solution and in inert soil less mediums....above 6.4 is the "danger zone"
And... "there's more than one way to skin a cat"

Arrgh, I'm way over tired and have more thoughts on this but need rest...talk later.

 

[petemoss]

Thanks for that chart, red! I've been looking for it because I've been searching for the proper PH range for my coco plants. My perpetual SOG began as a soil grow and has evolved into coco grow. Using a PH of 5.8-6.2 still gives me many signs of nute deficiencies such as yellowing and crispy fan leafs and slow growth. I think I'll start to treat my coco mix as an inert hydro medium even though coco is "high CEC" mix and try to run at a lower PH...about 5.2 and see if it drifts up.

 

[Oldmac]

It's my experience running Promix with cheap chem nutes - Shultz 10-15-10 that problems would start when the pH dropped below 6.2. Adding D-Lime and maintaining the pH 6.5-6.8 with better nutes gives me good results. So I'm doing a soil style grow currently with AN nutes.

I think if you want to run Hydro style with low pH, you will have a running battle with the D-Lime as it buffers the pH and will pull it up over time. Promix is a blend of peat moss, vermiculite and perlite with some D-Lime. You could mix your own or try a perlite/vermiculite blend or go to CoCo.

Hi Red,

Thanks also go out to you from me for the chart. Very interesting with what you have said about your experiences too, and your comments abt Pro-mx. I also think going in with a low PH creates a battle and buffering is a perfect way to describe the D-limes function.

I spoke today to a greenhouse grower, he told me pretty much the same thing. Only used different terms; promix has dolomite lime in it, that's to keep it from getting "sour", it will bring it back to "sweet", but also he added it releases calcium and magnesium to the mix. Since a majority of growers are using RO water there is no need to "meter" it into the nutient flow, it's already in the pot.

 

[Oldmac]

Hello 10K,

First I'd like to say I like it here and I think I've found a home.

But damn man, I saw your post early this AM and between reading your post, doing some research and reading more....I started my day late, all 'cause you got me thinkin'. Bothered me enough to go out of my way to see a friend at his greenhouse and ask him about pro mix. Since he used charming terms like sweet and sour I needed to ask him what PH he used. He said "shoot for 6". Told him that somene (Row) had found an info page from a nutrient mfg who recommends 5.8 - 6.5. He said to me "so how much different is that then what I told you? shit, just shoot for 6!" Well, like I said earlier, that's abt where I am now. Since this is a new grow op and we are fighting enviromental problems (growing in the basement from hell) I'm sure that I'm not getting maxium growth ATT so I am not real sure if I'm losing anything to PH.

That might change if I decide to add 20-30% perlite. Actually I hope to educate my partner and start to change over to an aero/fog ponic grow trays I have built and played with but not put into production yet. It just does away with a grow media all together. I'm having a hard time making him rethink all the things he thinks he knows abt growing, but he's comming around.

Thanks for reminding me that I can check the runoff to try and see what's going on. Years ago I had a stick in the soil type PH/mositure meter, and never saw major swings in the promix untill it was about 8-9 wks old then would sart to see a slow but steady climb, abt wk 12 it was offical....gone "sour". hehe gotta' luv it.

 

[Oldmac]

Hey Row,

I think maybe you really found the answer already. I'm just not sure if it's definitive.
Must sleep on it and see in the AM how I feel about this.

 

[Oldmac]

Eureka Row!

After devoting more then a day thinking, reading and talking about this topic with some other people, and having slept on it (for at least 4hours), I woke up and had me a "eureka moment".

Row, I think you have come up with the most definitive answer yourself, when you found the DutchMasters' reccomendation for Pro-mix. They clearly address soiless mixes, name Pro-mix and give a resonable yet short reasoning behind the recomendation. I happen to use DM products and have never had a problem with them. I use DM Gold in my personnel grow (3 stage Rockwool, drip to waste) and DM Advance with the Pro-Mix. I like and trust this company so I'd go with them on this.

Also you have seen for yourself it ran better at PH of 6 then when stated higher. Why not go to 5.8 and see what happens and if it gets better, drop it .2 more and run at 5.6, etc. Somestime we all just have to experiment a little and find what works best for us and our stiuation.

Great thought provoking thread Row, hoping it continues since I know a lot of people use Pro-Mix, maybe we can get some others to tell us what's working for them.

 

[10k]

Eureka Row!

After devoting more then a day thinking, reading and talking about this topic with some other people, and having slept on it (for at least 4hours), I woke up and had me a "eureka moment".

Row, I think you have come up with the most definitive answer yourself, when you found the DutchMasters' reccomendation for Pro-mix. They clearly address soiless mixes, name Pro-mix and give a resonable yet short reasoning behind the recomendation. I happen to use DM products and have never had a problem with them. I use DM Gold in my personnel grow (3 stage Rockwool, drip to waste) and DM Advance with the Pro-Mix. I like and trust this company so I'd go with them on this.

Also you have seen for yourself it ran better at PH of 6 then when stated higher. Why not go to 5.8 and see what happens and if it gets better, drop it .2 more and run at 5.6, etc. Sometimes we all just have to experiment a little and find what works best for us and our situation.

Great thought provoking thread Row, hoping it continues since I know a lot of people use Pro-Mix, maybe we can get some others to tell us what's working for them.

Not to diss your "eureka moment"...
But I must say that the manufacturers of nutrient packages tend to recommend pH ranges that work best for their products. You mention that you're using the dm gold line for your rockwool drain to waste. If you run this product at 5.8 instead of DM's recommended 5.5, you are in essence chopping mag uptake significantly and eventually endangering cutting down several other micros, plus p &k as the pH drift goes upwards from your 5.8 start.

As for your use of dm advance line in the promix, you'll get no argument from me as your running the dm products and not the GH Flora series chem nutes, which is what Row is inquiring about here.

For their product line, in their own words, Dutch Masters says...

"Check and adjust the pH 5.5 to 5.8 for Rockwool, Perlite, Clay, Aeroponics, Hydro or Coco users. 5.8 to 6.5 for soilless systems such as Promix or Sunshine mix."

 

[Oldmac]

Yo' 10k,

Point well taken about different Mfg may recommend different PH's to more suit there perticular product. So what does GH Flora series chem nutes have to say about promix?

But since Row stated it was better at a PH of 6, what would be wrong with his trrying to go down say .2 next run to see if he gets better or worst results. Might even to go lower in steps......and that puts it closer or even into the area you think is best. This is how I've dialed in or "fine tuned" things like PH or nutes strength. etc, regardless of the media I am using. Using common sence; just like knowing when to water soil container plants.

You mentioned my use of DM Gold in my RW drip to waste, I never said what I use for that. Again what I use there, I arrived at that thru trial and error. As for rockwool; I don't like using it, don't recomend it, pretty much hate everything about....I use it cause it fits my needs, and it fits my GI-grow. It is why I have spent some time money and effort building and experimenting with aero/fog ponic grow trays setup I hope to get up and running soon.

I'm still poking around to see what other Pro-Mix users (you know who you are) have been using with thier brand of nutrients.

 

[10k]

So what does GH Flora series chem nutes have to say about promix?

GH flora series is a hydroponic chem / mineral nute package. They say nothing about promix.

Flairform gives plentiful information about optimum pH ranges to avoid percipitation and damaged chem hydro mineral multipart nute solutions...
They advocate running a 5.0 to 6.0 range and proper mixing to avoid such solution damage.
http://www.flairform.com/hints/ph_optimum.htm