pH-alteration (downward) - what acids do you use, if any?

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pH-alteration (downward) - what acids do you use, if any?

Postby Iheartbougs » May 13th, 2018, 8:27 am

I've got the un-lucky circumstance of 8.0pH tap-water, so while I'm in the process of refining my rain-barrel setup (which is ~4.7pH in my area) I'm approaching the pH-problem with acids.

Phosphoric acid seems to be the ultimate go-to for this (General Hydroponics' "pH-Down" product is ~75/25% phosphoric/citric acids, for instance; botanicare's is pure phos.acid), however most of my specimen are bougies that are about as 'in-development' as can be, I love flowers like everyone else but am trying to push vegetative growth and really don't want that heavy phosphorous load that I'd get in trying to use phos.acid to bring 8pH water to 5.5pH....will be flowering out of control.

Muriatic(hydrochloric) seems OK but leaves chlorine which can accumulate....nitric seems best, though dangerous to get and work with - however, I recently found that sulfuric acid - aka, battery acid - was in-use amongst hydroponics gardeners w/ success, and I don't mind a higher Su load (compared to Phos!)

My problem is two-fold here - I've yet to find *any* way to actually use the product (ie how much to use to get the pH to X), as well as any 'final word' on what specific things to be sure of - people seem to say "just go to an auto parts store and get battery acid" but, frankly, I fear by-products/additives, am not really expecting generic battery acid to be some lab-grade sulfuric acid yknow?

Thanks for any thoughts on this one! I only found out my pH problem recently, had a bad chlorosis problem I couldn't get rid of no matter how much iron I threw at it, and finally found that it was basically pointless because at 8pH iron is virtually un-absorbable!
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby treeman » May 13th, 2018, 11:28 am

I used to use oxalic, citric and sulphuric. Sulphuric is dangerous so be careful. I think it's the best though. If worse comes to worst use pure vinegar.
Don't use hydrochloric.
Another alternative is to sprinkle agricultural sulphur on the mix. I need to look up my books for quantities......
Last edited by treeman on May 13th, 2018, 11:30 am, edited 1 time in total.
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby Iheartbougs » May 23rd, 2018, 5:14 am

treeman wrote:I used to use oxalic, citric and sulphuric. Sulphuric is dangerous so be careful. I think it's the best though. If worse comes to worst use pure vinegar.
Don't use hydrochloric.
Another alternative is to sprinkle agricultural sulphur on the mix. I need to look up my books for quantities......

What are the leftovers of vinegar? I've left vinegar outside in a bowl for days and it still has that stink...gotta say I'd be hesitant to use that when sulfuric is available (or phosphoric- I know it's the go-to, it's just that I want to keep a low phos load because it induces un-wanted flowering)

Was told on a hydroponics forum (which is what I consider most of my setups to be) that nitric is best but dangerous, that sulfuric is safe if you're a capable person (obviously bad in the hands of dummies ;P ), I don't mind the extra Su load that using sulfuric would give me....what're the extras left by vinegar?

(And while I like the idea of agricultural sulfur it's just totally impractical for me, it's already impractical for bonsai-in-general IMO (good for soils but not for our inorganic mixes & small containers, far too imprecise) but for me it's even worse because I have such a higher pH change to aim for as my tap is 8pH, I mean thankfully rainy season has started so will have my <5pH water for months but want to have it setup well before needed as I don't ever want to use 8pH tap water again after an issue w/ iron-deficient chlorosis, was supplementing iron and couldn't fix it til I added a ton of acidic peat-moss to the substrate and finally got some green back!)
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby treeman » May 23rd, 2018, 10:58 am

Iheartbougs"]
Another alternative is to sprinkle agricultural sulphur on the mix. I need to look up my books for quantities......
What are the leftovers of vinegar? I've left vinegar outside in a bowl for days and it still has that stink...gotta say I'd be hesitant to use that when sulfuric is available (or phosphoric- I know it's the go-to, it's just that I want to keep a low phos load because it induces un-wanted flowering)


The P definitely will not induce unwated flowering. Tha'ts a myth. However too much soluble P can be a problem in other ways. I would avoid it if you can use sulphuric.

Was told on a hydroponics forum (which is what I consider most of my setups to be) that nitric is best but dangerous, that sulfuric is safe if you're a capable person (obviously bad in the hands of dummies ;P ), I don't mind the extra Su load that using sulfuric would give me....what're the extras left by vinegar?


I've never used nitric but I know that concentrated sulphuric is extremely dangerous. You cannot even breathe the vapours. I don't think vinegar will add any ions to worry about.

(And while I like the idea of agricultural sulfur it's just totally impractical for me, it's already impractical for bonsai-in-general IMO (good for soils but not for our inorganic mixes & small containers, far too imprecise) but for me it's even worse because I have such a higher pH change to aim for as my tap is 8pH, I mean thankfully rainy season has started so will have my <5pH water for months but want to have it setup well before needed as I don't ever want to use 8pH tap water again after an issue w/ iron-deficient chlorosis, was supplementing iron and couldn't fix it til I added a ton of acidic peat-moss to the substrate and finally got some green back!)


I had a water pH of 10 for some time before I moved and regularly 9. I was able to grow azaleas with good colour. I used osmocote in the mix which acidifies because the urea is converted to ammonium. If you use a fertilizer with ammonium sulphate as the main nitrogen source during the summer (not winter) you should be able to manage things ok without acidifying the water.
Last edited by treeman on May 23rd, 2018, 10:59 am, edited 1 time in total.
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby thoglette » May 23rd, 2018, 4:11 pm

I use Ferrous Sulphate in my garden as I have limestone under the soil. Fe(II)SO4 lowers pH and adds iron, which helps deal with chlorosys (sp?)

It also kills broadleaf weeds in the lawn: apply on a dewy lawn in the morning and let the sun do the rest.

I haven't tried it in my potting mix
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby Iheartbougs » May 24th, 2018, 5:26 am

Thanks!!!

treeman wrote:The P definitely will not induce unwated flowering. Tha'ts a myth. However too much soluble P can be a problem in other ways. I would avoid it if you can use sulphuric.

What? Seriously? I've heard the phosphorous/flowering relationship from so many people including 'bougie specialists, nevermind that in-general phosphorous helps with blooming - am I missing something or are you really saying that changing the N::P ratio abruptly has no effect on flowering? I know you wrote clearly and hate having to ask you for clarification but that's just so contrary to what I've been taught and what I've seen (I've used high-P ferts to induce blooming myself, though it wasn't a controlled experiment so I was doing all the other things ie keeping it drier, reduced nitro etc etc)



I've never used nitric but I know that concentrated sulphuric is extremely dangerous. You cannot even breathe the vapours. I don't think vinegar will add any ions to worry about.

Nitric is the dangerous one, sulphuric is certainly to be handled with care but is routinely used in hydroponics (though even nitric is), I can't stress enough that I'd be using it safely and that the need to do that has no influence on which acid I go for..


I had a water pH of 10 for some time before I moved and regularly 9. I was able to grow azaleas with good colour. I used osmocote in the mix which acidifies because the urea is converted to ammonium. If you use a fertilizer with ammonium sulphate as the main nitrogen source during the summer (not winter) you should be able to manage things ok without acidifying the water.

I know but am trying to maximize growth not just get by (I don't really have bonsais so much as a collection of stock and pre-bonsai, so right now the primary focus for most of my garden is simply increasing girth on my primaries!) It's gotten warmer and we've had a more humid enviro so I can't tell what's attributable to what, but since starting to use pH ~4.5 water a few weeks ago I've had noticeably stronger growth but again it's mid-spring here so it could be entirely seasonal....though, that said, macro/micro-nutrient deficiencies are very commonly limiting factors and pH has a HUGE influence on that, I mean my tap water is 8pH, iron is barely available to the roots at that pH:
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby treeman » May 24th, 2018, 9:55 am

Iheartbougs wrote:
What? Seriously? I've heard the phosphorous/flowering relationship from so many people including 'bougie specialists, nevermind that in-general phosphorous helps with blooming - am I missing something or are you really saying that changing the N::P ratio abruptly has no effect on flowering? I know you wrote clearly and hate having to ask you for clarification but that's just so contrary to what I've been taught and what I've seen (I've used high-P ferts to induce blooming myself, though it wasn't a controlled experiment so I was doing all the other things ie keeping it drier, reduced nitro etc etc)



Here are 4 slides from a talk I recently gave. Hopefully self explanatory

fert1.JPG


fert2.JPG


fert3.JPG


fert4.JPG


So, in fact it's too much N which inhibits flowering not extra much P which promotes it.

Both fertilizer examples have the same P/N ratio.......27 divided by 5.5 = P/N ratio of 0.2. 4.8 divided by 18 = P/N ratio of 0.2
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Last edited by treeman on May 24th, 2018, 10:00 am, edited 1 time in total.
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Re: pH-alteration (downward) - what acids do you use, if any?

Postby treeman » May 24th, 2018, 1:21 pm

Iheartbougs wrote:


I know but am trying to maximize growth not just get by (I don't really have bonsais so much as a collection of stock and pre-bonsai, so right now the primary focus for most of my garden is simply increasing girth on my primaries!) It's gotten warmer and we've had a more humid enviro so I can't tell what's attributable to what, but since starting to use pH ~4.5 water a few weeks ago I've had noticeably stronger growth but again it's mid-spring here so it could be entirely seasonal....though, that said, macro/micro-nutrient deficiencies are very commonly limiting factors and pH has a HUGE influence on that, I mean my tap water is 8pH, iron is barely available to the roots at that pH:
Image


The p/mix industry here adds iron sulphate at 600g to 1kg of iron sulphate per cubic metre. This is because iron is needed in large amounts compared to other trace elements and bark (which is what the mixes are made of mostly) binds Fe. Adding Fe only from fertilizer often leads to deficiency. Iron is what gives the bark it's black colour. Unamended bark is likely to look pale and adding it later will probably not be enough. With the old school potting mixes made of peat, soil and sand, this problem did not occur or was much reduced. It's worth remembering that point as well when trying to supply Fe to plants. If you are worried about overly alkaline water, you should start your mix more on the acid side. About 5.5 for most plants. You could also consider adding peat to bring down the pH as well as give a good buffering against extreme pH swings. Many modern bonsai mixes have a very low buffering capacity. If you use lava, pumice, diatomite, and course bark type mixes you will be constantly fighting against pH swings. Including 15% clay (acidic) or peat, or both will help a lot. This is why we have the Australian Standards for our better quality mixes which by law need to have certain pH and buffering capacity parameters so you will usually get no problem from them even though your water may not be ideal. At least for a period of 2 years or so.
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