@HB I read your journals and in no way would argue with your results. However, what is consistent in your hydro grows is your observation of the need for more N when using Dyna with rockwool. My theory, backed up with some experience is this: Since the amount of Ammoniacal N supply is significant with Dyna, the N is not being processed very efficiently if at all because you lack the bacteria required for nitrification. Tap water is not a bacterial source because the water is chlorinated or sanitized by other means. Your rockwool is clean as are your nutrients, so how do you obtain these bacteria? You correct the problem by adding a more concentrated nitrate N (Grow) eventually reaching the desired result. So in effect, instead of a say 1-2-2 feed , you were actually getting a .6 -2-2 feed because the ammoniacal nitrogen was kept dormant. FYI coco and pro-mix/peat has very low of these bacteria also. As a remedy, any organic solution with composted poop introduced periodically would provide an ample supply these bacteria. I had almost identical symptoms as you did but instead of adding more N, I added some Botanicare Original Compost Solution just once and I was fine. (Fatman recommendation BTW)
As your Cornell reference states, bacteria is needed for nitrification. It also states that small grows are where you see more dramatic PH swings and that they are much more subtle in large greenhouse environments. In any case, I believe most greenhouses run drain-to-waste anyways so recirculating ph issues are moot in that scenario.
Reading @thecoolmans Plantex website, they stated that they use 100% nitrate N as a base in hydro and then use ammoniacal N as desired. I can see where a greenhouse say in Florida would shy away from Ammoniacal N because at lower temps, ammoniacal N is much less efficient so more auxiliary heating would be required. I experienced that with a bout of Ammoniacal toxicity when my temps were low to begin with but I was also growing in air-pots which exacerbated the situation of too low average temps in the medium.
I find it odd that you don't think DG wasn't 'designed' for hydro as I haven't bought pH up or down in over 30 months. Would you say 'General Hydroponics' makes food designed for hydro? If it is, you can have the six gallons that are collecting dust next to my DG bottles.
I don't think @coolman was being combative nor am I. He was just pointing out that in his view, formulas with high ratios of ammoniacal N is "odd" in a large scale commercial environment and he supplied supportive references supporting that with planex and the Florida University tables.
What would be interesting is to find out what other pro hydro ops use in inert medium grows and try to reach a general consensus. Much more reading ahead...........
