pH of pour thru 4.5...how to increase?

[Palasz]

Hi-

I have a few orchids (phals) that I keep and recently measured the pH of my water and also a pour thru. The pH of tap water with mixed fertilzer was 6'ish.. that seemed ok for my Phals..

I did a pour thru and the water collected measured 4.5...seemed a little low according to a recent lecture I atteneded.

How do you increase pH around roots?

Thanks,

Mike

[Royal]

Different forms of Nitrogen can have different affects on the substrate. If I remember correctly (not likely), the uptake of ammoniacal N reduces pH of the medium while nitrate N does the opposite. I may have this mixed up, but I do know that the source/form of nitrogen has residual effects on the substrate. It has something to do with the ions left over after plant metabolism.