pH adjustment

[netpumber]

Hi...

I've found these three recipies on net for a homemade propagation media.

1st

Formula of Tomato with banana
· 40 g of mashed banana
· 100.0 ml of tomato juice
· 10.0 g of agar agar
· 20.0 g of sugar
· 1.2 g of Tiamina (4 tablets B1 - Benerva)
· 900 ml of distilled water

HOW TO PROCEED:
· Prepare the ingredients separately (mash and cut).
· Warm the water.
· Mix all
· Spill in the clean flasks
· Present the lids not too tight and put silver foil above
· To put the flasks in the presure cooker and when the steam sounds, 20 minutes
· Wait until it is cold, close and to cover well the flasks.

And now just wait a few days...

2nd

Mediafor 1litre of orchid TC media)can also be use for germinating Nepenthes
1 banana
1litre of distilled water
2tablespoon of sugar
around a tablespoon of agar
a pinch of orchid fertilizer

first:
you put a banana in the blender with 1ltre of distilled water,then blend it !

Second:
pour it in pot and add 2tablespoon of sugar.

Third:
a pinch of orchid fert,add a tablespoon if agar then check the PH.must be something 5.4-5.8

someguys add agar when the media is poured in the jar.

you heat heat heat the media and after some heating,pour it into the jars and capped it but not tightly.put in microwave or pressure cooker.
for microwave,heat it for 20mins and after heating,close the cap tightly immedietly and leave it for 10days to see any fungus grow...

3nd

Media preparation for homemade flasking ! - Orchid Board

What is your opinion for these recipes ? Which one sounds better? I think No3 but it is little more difficult to make it than the other two.

Also i want to ask something on the first two (No1 & No2) recipies.. How we adjust the pH in these cases ?

Has anyone an idea ?

Thanks in advance..

[roby]

in Case 1 do not adjust the pH
the tomato is about 4.5.
pH is a logarithmic scale and then 100 ml of tomato with 1000 ml of water with a pH of 7, the pH of the solution is the correct value is 5.5

[netpumber]

Hmm yes you are right..but with the metabolism that seeds will do, there is no case the pH be changed?

[roby]

Probably yes, but remember that every 2 or 3 months you must replace the medium.
Anyway, for this problem would need a buffer substance, not something that changes ph.