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Aluminum Sulfate

mmcdermott1

mmcdermott1

Well I have been playing tug o war with my pH since I started this year because I have really hard water. I have been using vinegar (cause im cheap) but it doesn't maintain. The pH keeps shooting up around 7.5 and sometimes even as high as 8. The vinegar brings it back down short term but not for long.
So, I am stopping today to get some aluminum sulfate. A few questions:

1. I guess it just depends on the ph readings but how often should you have to give this?
2. How would you give this? Top spray? Bottom watering? Sprinkle it on top? I would imagine it needs mixed in the soil but thats kinda impossible in an already potted plant
3. How much would you give? I would assume start small, measure for a few days, and add as needed?
4. Does this stuff have a more long term affect on keeping the ph down then what vinegar does? In other words does it have a longer affect?

I have heard that vinegar, although it may measure ok in just water, quickly goes away once put in the soil. Not sure the if this is accurate but it is definitely not keeping my ph down to where it needs to be for peppers.
 
doing the control of ph with the plant there is not so advisable as you might shock the plant. The best thing you can do is to repot it. I made the mistake last time and I killed the plant. Dont do the same mistakes as me. Any neutralizing will create some by product and chemical reaction. If wanna do organic way its too slow.
 
what about powdered pine needles? Is there anything other than aluminum sulfate that can SAFELY bring it down? (not ignoring your last response redtail, just trying to get as many options as possible)
 
You could try the pine needles or dried oak leaves to see if it helps. If you can at least get it down to neutral, that should hold you over until the head outside.
 
you have high pH in your water

it might be you can lower the water's pH before applicating?

did i miss something?

if you just had some affordable acid source, like horse pee?(check the pH of that stuff)

maybe you could "collect" some of that for apply to the water? (maybe a slightly acid manure tea?)

i dunno, try using stuff you ain't gotta buy?
 
I've tried watering aluminum sulfate into my pots a few years ago. I don't know what the exact balance was, but I would put a pinch into some water mix well, test it, put a bit more in, test it etc. In the end it seemed to do the same thing as the vinegar is doing with you. The soil always ended back up to where it was previously. I never noticed any harmful effects to the plants doing it this way. I'm just guessing here, but it would seem that the soil would become more acidic over time and that a single application isn't really going to do much when watering it in. Although to me, that gives you the most control over a plant that's already growing because you can add more or less depending on soil readings.

Also, if your water is causing the problem and raising your soil ph I can't really see re-potting as the solution. Especially considering you'll still be watering with the same water. You'd have to find a different source of water or treat it AND repot it if you go that route. I could very well be wrong though.
 
Blister said:
I've tried watering aluminum sulfate into my pots a few years ago. I don't know what the exact balance was, but I would put a pinch into some water mix well, test it, put a bit more in, test it etc. In the end it seemed to do the same thing as the vinegar is doing with you. The soil always ended back up to where it was previously. I never noticed any harmful effects to the plants doing it this way. I'm just guessing here, but it would seem that the soil would become more acidic over time and that a single application isn't really going to do much when watering it in. Although to me, that gives you the most control over a plant that's already growing because you can add more or less depending on soil readings.

Also, if your water is causing the problem and raising your soil ph I can't really see re-potting as the solution. Especially considering you'll still be watering with the same water. You'd have to find a different source of water or treat it AND repot it if you go that route. I could very well be wrong though.
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For my organic hydro setups in the past I generally used high end ph/kh buffers. They come in a variety of ranges from 6-8+ and also maintain alkalinity which dictates the waters ability to maintain the ph level....aka it's "buffering capacity". Using the fore mentioned aluminum will drop the ph but oddest no buffer to hold it there effectively. Another thing you may want to consider is a reverse osmosis setup for the tap. You can get a 100 gallon/ day system relatively cheap. This would allow exact control over the water which will negate or combat ph issues in e soil. I've got a 50gpd system that filled a drum and shuts off with a float when it is full. It is awesome, good for lots of applications that require water free of TDS?
 
I have seen these posts about pH and people fidgeting about a ph of 6.5 or 7.5 so let me say something about this. The regular pH of rain water is not 7.0 as one may assume it is. The pH is actually 5.6 (not assuming acid rain here just the fact of carbon dioxide equilibrium). Therefore you could use rainwater to lower the pH. However a pH of 8.0 is not necessarily bad. The pH between 6.0-7.0-8.0 is fairly small compared to what mother nature could do. Unless your plants are suffering than I would do nothing. If you would like a pH of around 7.0 then use a pH buffer. Gatorade is a pH buffer and has good minerals. Has anyone tried using gatorade as a mineral supplement and a pH buffer? It would be interesting if you tried that. Again having a soil pH of 7.0 isn't wise because in nature its impossible therefore why would you try to force it to be that in your pots just for the sake?
 
well i have noticed in the past few days, some of my plants are starting to curl. I know its not over water or over ferts..or fungus or bugs...and from what I have gathered on here...could be a nutrient lock because of the high pH of my soil. You agree or think not?
 
You most likely have induced a buffer solution (either from the phosphorous additives in your potting soil or using ionic salts for fertilizer such as calcium or magnesium salts) and the equilibrium is around 8.0. Therefore adding stuff to your soil will only temporarily bring it down since buffer solutions of any strength retain the same pH roughly. Since you do not know how much you will need to add to bring it down, your shooting in the dark. The wisest decision would be to transplant the plants into a known pH soil. Trying to modify the equilibrium will most likely kill your plants simply because you have no idea what you put into the soil to buffer the pH as is observed. Buffer solutions can be very potent and require very strong acid concentrations to neutralize.
 
mmcdermott1 said:
Actually OOnick...I have no idea why,but my RO water is actually higher pH than my well water. That kind of baffled me
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Depends on the ph of the well water. If your ro is coming out anything other than neutral there is something wrong with the ro or the method of testing. The ph strips and most cheaper test methods from garden stores should not be taken literally beyond a full interval (ie reading 6.5 on a ph strip is most likely not actually 6.5 as it is somewhat subjective). A proper Ro/Di unit should come out with zero TDS and neutral ph.

@ lonelyhab, they is a gigantic difference between a ph of 6 and 8. Each interval is literally 10 fold. Ph much above 7 can lead to nutrient deficiencies from my indoor exp. Though I would assume that growing peppers holds the same water truths that hydro and reefing do...... In that splitting hairs over parameters that are close to the mark can cause more stress than letting things be.
 
There are so many possible variables, but I think you probably want to try other things before adding aluminum sulfate. If we are talking about seedlings, I think you'd be best switching to RO water. Check the pH of the RO water after you add some organic or mineral fertilizer, it should be down below 7.

Here's what Wikipedia says:

"Reducing soil pH

See also Soil acidification

* The pH of an alkaline soil is lowered by adding sulfur, iron sulphates or aluminium sulphate, although these tend to be expensive, and the effects short term.
* Urea, urea phosphate, ammonium nitrate, ammonium phosphates, ammonium sulphate and monopotassium phosphate also lower soil pH.
* Fertilizers often also effect a slightly more acidic soil since this increases uptake of nutrients.
* Decayed vegetable matter, compost, stable manure, urea, etc.
"

I'd just use water w/ either compost tea or a mineral fertilizer for a while before resorting to the aluminum sulfate. If these plants are eventually going into the field or bigger pots then compost and gypsum are good additions.
 
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