Soil pH is too high ..

i tested the run off water from my plants a while back and noticed that it had a pH of about 8-9. i thought this was very strange as i was watering with water that had a pH of 5.5-6 and the soil i was using (plagron royalty mix) is supposed to have a pH of 6-7.

after realising this i got a 2 litre pot and filled it with the plagron soil. i then began to water it with acidic water (pH 4) i kept doing this till the run off water was about 6.5.
i did the same with another pot, this one had bio bizz all-mix in it and it took pretty much the same amount of acidic water to bring the pH down to 6.5. (about 10 litres of water for each pot)

this sound strange to anyone? any ideas why this is happening?

Did you add lime to your mix? If so, what amounts?

no i just took the soil straight from the bag and put it into the pot.

i tried again, this time using plagron light-mix. i put the soil into a 2l pot and watered with 1.5 litres of pH 5.5 water. the run off was pretty much the same on the colour chart.
maybe the time releasing nutrients in the other soils are interfering with the pH?

iv been using time releasing soils so that i dont have to mess around with fertilizers. but after these tests i think the light mix with a terra grow/bloom fertilizer program is the way to go.

big bee said:

no i just took the soil straight from the bag and put it into the pot.

i tried again, this time using plagron light-mix. i put the soil into a 2l pot and watered with 1.5 litres of pH 5.5 water. the run off was pretty much the same on the colour chart.
maybe the time releasing nutrients in the other soils are interfering with the pH?

iv been using time releasing soils so that i dont have to mess around with fertilizers. but after these tests i think the light mix with a terra grow/bloom fertilizer program is the way to go.

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Yeah, I'm not a big fan of time release myself, I like to control and know exactly what I put in. I'm not sure what's going on, I guess you maybe just have to adjust accordingly until you get a finger on it.