Sooo do you PH water with Pro Mix or not?

Trying pro mix bx for the first time. I'm seeing a lot of mixed info on ideal PH range and if PHing water is needed due to the lime buffer. Since there is always a lot riding on each grow, I'd rather not fuck around and find out. Is Pro Mix actually treated like semi soilless (hydroish) at around 5.5-6.0 PH? Do you actually need to PH water going in or will that natural buffer take care of it? Ideally I could just put in my regular water at 7.7 PH or my nutrient solution which typically acidifies the water to around 6.5-6.7. Will I need to PH the water down to like 5.8 so PH will rise as dries?

RuggedWombat said:

Trying pro mix bx for the first time. I'm seeing a lot of mixed info on ideal PH range and if PHing water is needed due to the lime buffer. Since there is always a lot riding on each grow, I'd rather not fuck around and find out. Is Pro Mix actually treated like semi soilless (hydroish) at around 5.5-6.0 PH? Do you actually need to PH water going in or will that natural buffer take care of it? Ideally I could just put in my regular water at 7.7 PH or my nutrient solution which typically acidifies the water to around 6.5-6.7. Will I need to PH the water down to like 5.8 so PH will rise as dries?

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6.5-6.7 is a bit high but with proper watering-runoff each watering should be fine just dont let it get dust dry. If doing full run 3-4 months in 1 pot add some extra lime couple table spoons per pot.

thumper60 said:

6.5-6.7 is a bit high but with proper watering-runoff each watering should be fine just dont let it get dust dry. If doing full run 3-4 months in 1 pot add some extra lime couple table spoons per pot.

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Any downsides to amending with lime? What lime source is best for this medium? I'm running 7 GAL fabric pots so maybe 2 tbsp per pot? I'm assuming lime can't be top dressed mid grow and would require an up potting if PH becomes unstable? I was thinking 5.8-5.9 would be my normal target PH as I'm assuming PH rising as it dries is more of the concern. Atleast that way it starts in an optimal hydro range and if it rises it will still be in a good spot.

5.8-6.3. No problems. Lime takes a long time to go away, there's no need to add more in a grow cycle. If you're reusing it well maybe that's something to think about.

I've been aiming for ~6.0 though try to keep it in the 5.8-6.2 window.

Jjgrow420 said:

5.8-6.3. No problems. Lime takes a long time to go away, there's no need to add more in a grow cycle. If you're reusing it well maybe that's something to think about.

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And with a tap of 7.8pH the water is probably adding 80-120 PPM of carbonate each watering

7CardBud said:

And with a tap of 7.8pH the water is probably adding 80-120 PPM of carbonate each watering

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My tap is about 210 PPM or so. What are you referring to with the carbonate? The hard tap is already adding lime with each watering? The lime also buffers closer to 7 anyway I believe? So if anything always starting lower would be best I would think.

I have switched to a SIP with organic soil, but I did a pretty decent grow in ProMix Bx, with a little added perlite and some garden lime, using maxibloom. Sort of a drain-to-waste deal. I def had to ph up the maxibloom, which is real acidic.

LeastExpectedGrower said:

... I've been aiming for ~6.0 though try to keep it in the 5.8-6.2 window ...

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I have been using a pH of 6.0 - 6.1 when growing in either Pro Mix or Sunshine Mix.

RuggedWombat said:

Any downsides to amending with lime? What lime source is best for this medium? I'm running 7 GAL fabric pots so maybe 2 tbsp per pot? I'm assuming lime can't be top dressed mid grow and would require an up potting if PH becomes unstable? I was thinking 5.8-5.9 would be my normal target PH as I'm assuming PH rising as it dries is more of the concern. Atleast that way it starts in an optimal hydro range and if it rises it will still be in a good spot.

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I add 2 tbsp to 3 gal pots before up potting, 7 gals of promix will grow trees how long you plan to veg the plants, I veg 30-40 days then go to flower in 3 gals plants end up 3-4 ft tall.

thumper60 said:

I add 2 tbsp to 3 gal pots before up potting, 7 gals of promix will grow trees how long you plan to veg the plants, I veg 30-40 days then go to flower in 3 gals plants end up 3-4 ft tall.

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Well 5 gal pots seem to dry out every 2-3 days and I'm hoping to get less maintenance. I'm growing in a 2x4x5 tent and I don't have the room/electrical capacity to run the hydro setup I want so this seems to be the closest. I suppose I could always switch to a non fabric pot? There are some auto watering methods with soil like mediums, but I'm not looking to invest a bunch more when I will probably switch to hydro next summer or so. Are you doing 30-40 days from sprout or first true leaves? I'm coming off a decent meph auto harvest, but I'm looking to get a pretty solid photo grow again and make enough to perhaps start extracting. It's sugar cane from IHG so definitely not trying to fuck these up experimenting with pro mix.

RuggedWombat said:

... Well 5 gal pots seem to dry out every 2-3 days and I'm hoping to get less maintenance. I'm growing in a 2x4x5 tent ...

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5 gallon plastic Home Depot/Canadian Tire buckets work in a 2 x 4 x 5 tent. With Pro Mix or Sunshine Mix, I find that they need watering every 4 days - and you could stretch that out to 5 days. Plants do well in those soilless mixes.

RuggedWombat said:

My tap is about 210 PPM or so. What are you referring to with the carbonate? The hard tap is already adding lime with each watering? The lime also buffers closer to 7 anyway I believe? So if anything always starting lower would be best I would think.

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The bulk of minerals in hard water are calcium/magnesium carbonates-lime. That will build up over extended use.

You can neutralize that by adding acid to the feed solution or by using a potentially acid fertilizer.
GSTIPS-9 PRO-MIX Biofungicide - Disease Prevention (tallerhort.com)
A fert with about 250lbs/ton potentially acidity would be in the right ballpark.

I know Jack's list their potential acidity/alkalinity on their bags. You can probably find the info of other brands with an email or call.

7CardBud said:

The bulk of minerals in hard water are calcium/magnesium carbonates-lime. That will build up over extended use.

You can neutralize that by adding acid to the feed solution or by using a potentially acid fertilizer.
GSTIPS-9 PRO-MIX Biofungicide - Disease Prevention (tallerhort.com)
A fert with about 250lbs/ton potentially acidity would be in the right ballpark.

I know Jack's list their potential acidity/alkalinity on their bags. You can probably find the info of other brands with an email or call.

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I've been using Dynagro FP and bloom. Protekt is a big no as it makes it even MORE alkaline. I have a ton of PH down so maybe I'll just PH down to 6.0 or so with every feeding? Does adding PH down actually help prevent the buildup or does it just keep the PH in a range where absorption is optimal? Just curious if flushing would be necessary with the former.

6.5-6.7 is a little too high for promix. I like my ph around 6.0-6.3, but when I use jacks 321 it lands right in the ballpark and I dont need to adjust. I also feed 2-3x a day in 5 gallon pots.

RuggedWombat said:

... Does adding PH down actually help prevent the buildup or does it just keep the PH in a range where absorption is optimal? ...

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pH down - which in my case is 20% phosphoric acid - keeps the water within a slightly more acidic range which is better for peat based mediums. In that respect you do make more nutrients accessible to the plants and will reduce any potential build up.

A couple of years ago I contacted PT Horticulture who markets Pro Mix and asked. It was they who recommended watering with the source water pH between 6.0 - 6.1. Been doing that ever since and have not had any problems.

RuggedWombat said:

... Just curious if flushing would be necessary with the former ...

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Don't overfeed and use the recommended pH and you should never need to flush.

I will water only the last 1 or 2 times before chop but there is no flush. We've all heard about it ... that wasteful practice of pouring plain water through at something like 5 times the volume of the pot ... myself and others here on RIU have not found that it is not necessary.

I'm not sure what you're thinking here. It's really alot easier then you're making it. Don't add in anything to change the ph. When you feed, adjust the pH to your desired level. That's it. If you use silica, add it in first stir well, wait a few mins ph adjust and add in your nutes. People been using promix for decades. Don't need to reinvent it.

Sorry to seem daft @Jjgrow420 ... but was your most recent post for me or the originator? Cause your suggestion above is how I water. Add my nutes to the 4L of water, "shake well", adjust the pH to between 6.0 - 6.1 then give it to the girls. I give them said TLC every 4 or 5 days.

And they return that love about 11 weeks after I flip to 12/12.

StareCase said:

Sorry to seem daft @Jjgrow420 ... but was your most recent post for me or the originator? Cause your suggestion above is how I water. Add my nutes to the 4L of water, "shake well", adjust the pH to between 6.0 - 6.1 then give it to the girls. I give them said TLC every 4 or 5 days.

And they return that love about 11 weeks after I flip to 12/12.

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It was for op. It seems he's making mountains out of mole hills.
Adding lime, flushing, etc etc.....
It's really alot easier than he's making it out to be.

StareCase said:

Sorry to seem daft @Jjgrow420 ... but was your most recent post for me or the originator? Cause your suggestion above is how I water. Add my nutes to the 4L of water, "shake well", adjust the pH to between 6.0 - 6.1 then give it to the girls. I give them said TLC every 4 or 5 days.

And they return that love about 11 weeks after I flip to 12/12.

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Do you plain water feed at all?