I recently bought a bag of "Evergreen" sphagnum moss peat.
Today I got round to looking into its pH adjusting capability.
Summary Looks like just as good as Shamrock ! Yea! and is available near Bristol.
If you have nowt better to do then carry on reading :-) :-
Using some (rather old) BDH Universal indicator I got these pretty colours :
Indicated by arrow1 is the change in pH of rain water when the peat is added.
(B) is rain water that has been standing open to the air for a few days and is reading a pH of about 6. The camera has not picked up the colour very well but by eye it was on the yellow side of green, ie slightly acidic as expected due to dissolved CO2 and no buffer.
(C )After mixig with peat and standing for 1/2 hr the rainwater became acidic at about pH3.5 (red masked a little by the brown of the peat)
(E)is my tap water, very hard and alkaline, about pH8
(D)after soaking the peat it becomes redish, not quite as red as the rain+peat, so about pH3.8 ish, but still a very impressive acidification considering the buffering of the bicarbs in the tap water.
This change shows the character of my tap water and may indicate the sequestering ability of this peat (more about that below). The last time I measured the tap water there was about 300ppm of bicarbonates and 50ppm sulphates, ie. 300temporary and 50permanent hardnesses.
So the boiled and cooled tap water (F) has become very alkaline at about pH10, due to the decomposition to insoluble carbonate.
I have seen on some websites that tap water can be softened by boiling (true in many cases, in my case it softens from 350ppm total to 50ppm total) and they say can be used in an emergency in place of absent rain water. Well, at the alkalinity of (F) I dont think it would do a CP much good !!
Alas my chemicals for measuring hardness have expired so I cant measure the sequestering ability of the peat. ( To replace my EriochromeBlack T indicator alone would be £22 for 25g (pnly about 1oz. eeek!) from Japan plus EDTA ) so I have to guess !
[are you still awake, tell me if I have this next bit right cos I am not a professional chemist ! ]
An unscientific small handful of peat in a glass of tap water was all that was needed to turn it well acidic (arrow2) which means that all the calcium and magnesium ions have been sequestered, liberating CO2 thus softening and acidifying the water such that it would be suitable for carnivorous plants and sensitive tropical fish. ( I think ! but dont take my word for it !! dont want to be responsible for millions of dead CPs !!! )
So, in summary, Ian said a few days ago that "Evergreen" was good stuff. I think he is right !
In fact I think it is every bit as good as the "Shamrock" that I used to use and may even be a teensy bit better.
Just for illustration and calibration (A) on the left is a few drops of vinegar in rain water, about pH3 and on the far right ( G if I had remembered to lable it !) is a few grains of sodium bicarbonate in rain water (from the kitchen baking department ) about pH11
Phew, my fingers hertz.
Edited by MalcolmP, 17 June 2012 - 21:02 PM.