Check out:gpodio said:Urea is another nitrogen source however both of these alternatives could possibly cause some issues with algae growth. I think I'd stick to KNO3 personally. Others might have better alternatives.
Very soft, probably rivals San Fran water.plantbrain said:Well you likely have soft tap water in NY, so Ca(NO3)2 would work just dandy and add some MgSO4 baking soda and that would take care of a lot for you fast.
From the sound of it, it's difficult to keep the stuff out of solution. It will make its own!Calcium nitrate has been used by a few folks mainly for the Ca and the ease of getting it to dissolve vs CaCO3.
Tom,plantbrain said:I know of no upper limit on Ca levels, I've been to 440ppm.
As far as K+, I went well above 50ppm recently. Erik said he went to 100ppm K and we both grow Ammannia and funny odd plants etc.
I know the high K+ thing is a bandwagon, but whatever works as long as the K+ is not limiting.