How do I lower my PH in my solo cups?

jswieton

jswieton

I was wondering what is the best method to lower my PH in my solo cups?  My PH in my cups has been a steady 8 since I planted them.  I’ve tried testing the soil with both a probe and a soil test kit and in both tests  my growing media, which primarily consists of peat, seems to be a bit Alkaline. 
 
Without damaging my young plants, what is the best method to lower my PH to get it into the low 7 or high 6 range?  I was thinking about sprinkling some top dressing of dolomite lime and watering it in but I’m a litter nervous I might kill or damage my plants.  Can anyone give me a little guidance with what method/treatment would help bring down my PH into the proper range?
 
Lime will raise the pH, not lower it
Aluminum sulfate will lower the pH. Add it into the liquid you water them with and aim for a pH of 6-6.5
 
First things first - how old is the mix that is in the cups?  Did you make it, or buy it?  Secondly, what are you feeding them?
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If your plants aren't showing any signs of nutrient deficiencies, then don't get in a hurry to make corrections.  Figure out what is actually causing the PH to be in that range, and resist the urge to be reactive to every little thing that seems wrong.  If you start trying to correct PH without understanding why it is where it's at, then you may end up chasing it back the other direction, later on.
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As you've posted, we have no idea whether or not you have anything in your potting mix or nutrient that could act as a buffer, once your setup is established.
 
I’m using my own mix.  It consists of peat moss, Perlite, worm castings, glacial rock dust, humic acid, and mycorrhizae. I started my plants the first week of January.  At this point, most of my plants have two true sets of leaves and I have only fed them once at half strength.  I used Alaska fish emoltion and Neptune’s Harvest seaweed fert.
 
jswieton said:
I’m using my own mix.  It consists of peat moss, Perlite, worm castings, glacial rock dust, humic acid, and mycorrhizae. I started my plants the first week of January.  At this point, most of my plants have two true sets of leaves and I have only fed them once at half strength.  I used Alaska fish emoltion and Neptune’s Harvest seaweed fert.
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It really doesn't make any sense that you would have an alkaline PH problem, with that list of ingredients.
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Alaska fish should also be slightly acidic, as would the seaweed.
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What is the PH of your nutrient solution, before you add it to the cups?


 
 
solid7 said:
 
It really doesn't make any sense that you would have an alkaline PH problem, with that list of ingredients.
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Alaska fish should also be slightly acidic, as would the seaweed.
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What is the PH of your nutrient solution, before you add it to the cups?

 
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I tested my nutrient solution and it is 6.5 but when I test my water by itself it is 8.0.  I have limited the amount of nutrients that I have given my plants up until this point.  Perhaps once I start feeding them full strength doses it might correct my problem.
 
jswieton said:
I tested my nutrient solution and it is 6.5 but when I test my water by itself it is 8.0.  I have limited the amount of nutrients that I have given my plants up until this point.  Perhaps once I start feeding them full strength doses it might correct my problem.
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Your solo cups don't have enough buffering capacity for the volume of water that you're applying.
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You can PH correct the water, if you like. But if you aren't showing signs of deficiencies, I'd just leave it alone. The problem will work itself out as you go up to larger containers, at which time you'll need to PH your nutrient, anyway.
 
solid7 said:
 
It really doesn't make any sense that you would have an alkaline PH problem, with that list of ingredients.
.
Alaska fish should also be slightly acidic, as would the seaweed.
.
What is the PH of your nutrient solution, before you add it to the cups?


 
Click to expand...
 
An FYI for everyone here- Seaweed extract is generally alkaline with a pH of 9-10
Take into consideration that this will then be watered down so heavily it won't differ much from the liquid you stick it in
 
But- it's not acidic, it's basic
 
Powelly said:
An FYI for everyone here- Seaweed extract is generally alkaline with a pH of 9-10
Take into consideration that this will then be watered down so heavily it won't differ much from the liquid you stick it in
 
But- it's not acidic, it's basic
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I stand corrected. You are correct. Probably closer to 8-10, but correct, nonetheless.

Fish emulsion or hydrolosate is typically on the order of 5-6.
 
Peat moss is also quite acidic as far as soil additions go. It can even be used to lower the PH in pots etc by top dressing.
In short, it does not sound like you have a high PH issue. Sounds like your testing your soil / slurry using normal tap water.
 
You need to test using PH neutral water.
 
edit; to answer the OP's actual question. If you are still wanting to lower the PH, then sulphate of iron would be better than aluminium sulphate.
Aluminium sulphate is way too harsh and leaves too smaller margin for error. especially in something as small as a cup. Sulphate of iron also lowers the PH but is not as harsh or as unforgiving as the other.
 
Flowers of sulphur / elemental sulphur would be preferred but takes some time. Personal experience has seen improvements very quickly with fine/powdered sulphur though.
 
The other option is to top dress with peat, or mix some of it into the soil if possible.
 
You can add a spoon or two of vinegar as a quick solution to lower soil pH if it blocks nutrient availability to your plants. I sometimes water with diluted coffee or add some coffee grounds into the soil as well. Well I usually don't have soil pH issues, because I like to mix decent amount of peat moss in, which makes the soil acidic.
 
 
willard3 said:
  Exactly the opposite, lime juice will lower the Ph.....it's acid
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