should i worry about water PH or does soil PH adjuster compensate?

[vindiesel]

i'm using RODI water to water plants which are in promix bx. promix bx contains lime and i think something else as PH adjusters. my water is alittle high, at 8.0-8.1. i am thinking about using PH down to get it down to around 6.5, but the soil supposedely will "adjust" ph. plants are about 11 days into veg and look healthy and everything good, so that's why i'm not sure if i should lower water ph or rely on adjusters in soil...i have not started adding any nutes or anything at all yet. just 80% promix, 20% extra perlite. PH down and maybe cal~mag will be 1st things i may throw in. thanks.
vin

 

[wafflehouselove]

tagged, i would like to know the answers to this. Some people say soil is a ph buffer then some say always water your soil from ph 6.3-6.8.

 

[Guest]

Sometimes you have to water with very low ph water to offset the natural tendency for soil to rise in ph. The more ppm's go down, the higher the ph. Thus, the more that is taken up, the more the shift is upward. I get my water down to 6.0 and below to 5.5 even watering in soil. I think its the most vital part of growing, even above where the nutes come from. If you have ever read someone's journal (especially in hydro) you can see just the roots change the general ph constantly. An easy way to learn is to just test different things on a plant when you see a problem. I found that when I thought it was a N def. in veg, it was always ph instead.

PH your water, no matter what. Its like going on a trip and not knowing whether its 500 km or miles.

 

[Stalldaworld]

test the runoff's ph... if the lime in the soil is working the runoff should be in a acceptable range.. if your nervous about it add a little more lime (to last the whole grow) since your water is high and the nutes might bring it up as well.

 

[Guest]

My friend used to have all kinds of problems with nutrient lockouts and strange deficiencies when he used to use ph down (phosphoric acid, in his case) Mind you his water was quite hard (alot of calcium) so that may have played a role as well.He used to ph the water down to 6.5, runoff 6.2. Now he doesn't use it anymore and lets the dirt manage the ph, plants have never been healthier.When my friend waters with ph 7.6, the runoff is ph 6.2 -soil is promix hp.Some people swear by ph down and thats fine if it works for them, in my friends case he obviously didn't need it and the way he looks at it if you can eliminate something, simplify the process without causing any harm then why not.If your plants are healthy, the old saying "if it ain't broke don't fix it" should apply, but testing the runoff is always a good idea first.Some may disagree with me and thats fine, it's just my opinion.

 

[Guest]

I would say his problems probably came from ph down being made from phosphorus, which overdone can lockout a variety of nutrients. I think people with more acidic soil (peat) need more buffer. I use a soil composed almost half of compost which is supposed to naturally buffer around 7. My ph would sometimes be at above 7 because if you don't add enough to lower it and keep it stable, it will keep drifting up higher and higher. A lot of people have to add dolomite lime because their soil has a lot of nutrients in it. If you are a light feeder (I definitely am) with most plants, you have to understand less nutes means generally higher ph. If you have high ph water already, you are going to probably have to deal with high ppms. This means less nutes, therefore more ph regulation. If you have foxfarm and lightwarrior mixed up with pbp, your going to have a ph that can probably stay pretty decent with a nice amount per square foot of dolomite lime. Some people can get away with never testing the ph, its good to know whats going both in and out. Test your soil, before you believe what the package or what anyone else tells you. The fish aquarium water testers work good and you can get them at wallyworld.

 

[vindiesel]

i use my pinpoint marine digi ph monitor i use on reef tank...i don't know what to do. use ph down or leave them be. maybe i'll go get a soil ph tester at HD. i guess the PH of soil is really what matters....right?

 

[sirgrassalot]

I've never used a pH device & don't own one, my water is 7 even I use BX or HP. I'm using Fish Emulsion & PBP Bloom with PK-13/14. I'm told by my mentor my pH range for Veg is 6.o to 6.8. Bloom will be 5.2 - 6.0 in Pro-Mix. Yes they could change my water in the big city in fact they may have in the last 5+ years, its made no difference.

As far as I know you should be able to grow without it using these or similar nutrients. Since you're a little high it'll be good to check yours, sorry or at the first signs of pH trouble get her tuned in. Again I've never pH'd my soil or pro-mix grows. You want to check your 'run off' pH.

 

[Dr Dog]

Good thread

Vin Keep asking questions, you ask good ones

 

[wafflehouselove]

Last time i test my runoff it was really weird. I flush the plant fully with phd water of ph 6.3 but the runoff kept coming out 7.4 i mean i must have ran about 20 gal of water through this 12inch pot. What does that mean?

 

[vindiesel]

i'm gonna check in a couple hours when i water and will let u guys know what it tested for water and then the run off. if it's around 8 before watering, and run off turns up to be above 7, then i guess i should use alittle PH down, right?

 

[vindiesel]

just checked, water right from RODI unit, 8.15. runoff water 6.1...i guess i'm ok.....

 

[sirgrassalot]

just checked, water right from RODI unit, 8.15. runoff water 6.1...i guess i'm ok.....

and the plants are looking fine, it looks like you're good to grow.

 

[Guest]

Last time i test my runoff it was really weird. I flush the plant fully with phd water of ph 6.3 but the runoff kept coming out 7.4 i mean i must have ran about 20 gal of water through this 12inch pot. What does that mean?

Hard to know what it means without knowing a lot more information.

12" pot. 5 gallons? more/less?

What was the soil makeup?
How much organic material?
What percent was compost?
What percent was peat?
What kind of peat?
Ratio of organic material to inorganic(perlite, etc.)

I could go on and on.

Why pH is what it is depends on 1) the soilless mix's original composition, and 2) what has been added to the mix since....including water. Then factor in what the plant has removed by growing. Plants remove Ca++, K+, and Mg++ cations as they grow and replace those cations with H+ cations to keep the chemical equation balanced...and what runoff and/or flushing removes them also, those basic cations being water soluble

Flushing large quantities of water through a pot...whatever else it does, or might do...tends to wash out the major cations of Calcium, Magnesium, and Potassium. In soils with a lot of organic material, these cations are replaced by acidic Hydrogen cations (H+) tending to lower the soil pH if nothing else is done.

This is why in nature places with lots of rainfall tend to have acid soils. The large amount of rain washes out the water soluable Ca++, Mg++, and K+ cations. Depending on the soil composition these cations are replaced by Hydrogen H+ cations, or in mineral soils, Aluminum Al3+ cations....acidifying the soil over time.

Sooooooooo

What to do when your soil pH is too high or too low?

Perosnally, I would reviwe the soils original content and what I have put in it since. That usually tells me both why, and therefore "what to do".

This is why it is critically important to know exactly what is in my soil mix. If you make a good mix, you simply won't have pH problems if you treat it right.

I would strongly recommend reading BurnOne's Sticky on Organics for beginners....Whether or not you grow organically. It's good info and would save a lot of hassle for many of you.

And I am NOT trying to be a smart ass here.

I'm trying to show I approach solving problems. Soil pH can surely change. So in trying to find out why it changed, you need to know some basic facts. If you don't know those basic facts, I don't understand how you can rationally do anything constructive to correct the problem. You are essentially, "Guessing".

pedro

 

[wafflehouselove]

ty pedro,

12" pot. 5 gallons? more/less?

What was the soil makeup? FFOF
How much organic material?
What percent was compost?
What percent was peat?
What kind of peat?
Ratio of organic material to inorganic(perlite, etc.)

Actually the soil i was using was just straight up FFOF, i was watering all good and everything was looking good like its suppose to be then when i started seeing the first sign of def which was cal thats when i figure those stuff in FFOF is depleting so i add a light nute mix of fox farm grow big ph'd at 6.3, then i kept that schedule with watering then light nutes. then after that i never seen any improvement everything just went bad from there on. Ok one question if all those stuff in the FFOF depletes can i start using synthetic nutes ph'd at 5.5 all the way through? I've used synthetic nutes on a local nursery potting soil here with nothing in it before and everything was good, when i flushed that sign throughly everytime it keeps coming out 7.0 ph thats with plain water no matter what the ph'd water was, then when i add a lil nute and check the runoff the ph goes down. I guess that soil is better then FFOF?

 

[vindiesel]

i'm good ph 8.1 goin in, 6.1 draining out...thanks.

 

[Guest]

ty pedro,


Actually the soil i was using was just straight up FFOF,....

That is probably the root of your problem. FFOF straight up doesn't have enuf dolimite lime in it for cannabis IMO. And that is probably why you had Calcium problems. Lack of lime will cause pH issues too over time as watering leaches water soluble cations out of the soil.

(see my post tonight over on the organics forum about organics and pH)

This is why I stress to folks to read BurnOne's Sticky on LC's soil mixes. It is SOOOOOOOO important to get your soil mix made right BEFORE you ever put a plant in it. And proper liming of a soil mix is critical. It can be a VERY difficult problem to correct after the fact.

I'm not lecturing you, but that's just my very long held opinion on growing anything, be it a house plant or cannabis.

Soilmixes("Soiless" mixes), be they storebought, or ones you make from scratch....MUST be fine tuned, so to speak, for the plants you want to grow in them. It doesn't mean they have to have 57 different amendments. But it does mean they must be appropriate for the plant. FFOF NEEDS more lime IMHO to grow cannabis. I know others will disagree, but that's my opinion about FFOF....as well as some other commercially available potting soils.

Good luck!!

pedro

 

[Guest]

Something else about FFOF and many other commercial potting mixes.

They don't have near enuf perlite for my growing style (I do like slightly more perlite than is in LC's soil mixes, but his will work just fine for most folks). I just like my soils to be light and well draining...meaning they drain fairly quickly...and the soils absorb moisture as evenly as possible.

So I make sure my final soil mix is about 33-40% perlite.

Soils that stay wet too long because they don't drain well, can cause all sorts of problems....one of which is they become more acidic more quickly.

I screen commercial potting mixes, composts, and worm castings. I get all those big hunks of shit out of there. This makes for a much better soil texture that will transport water more evenly. Those big hunks have no nutrient value anyway. They just take up space and screw things up IMO. get them out. Run your dolomite lime through a fine strainer too. Small particles of dolomite lime become incorporated in the soil MUCH quicker.

pedro

 

[Guest]

i'm good ph 8.1 goin in, 6.1 draining out...thanks.

You talking about water only or nute mixture? If water, why not correct it? And if nutes, what nute arew you using that makes a alkaline mix? Why would you put 8.1 anything into your grow? Why not pH it down to 6.0-7.0 with something like a lilbit of EJ Grow?

ph correction is only needed if whatever you are applying is over 7.0. If it is below 7.0 (acidic) you don't need to correct it unless it is below maybe 4.0...and again the question is if what you're putting on is below 4.0 WHAT is it?

Personally, I don't like using phosphoric acid or nitric acid for pH down correction.

Pedro

 

[wafflehouselove]

pedro if a soil that have nothing in it just straight up soil with some perlite can i use synthetic nutes at ph 5.5 and it will work? Does FFOF turn into soil with nothing in it after i use up all the stuff in it?