Roger said: "For the common case substrates *should* lose fertility over time, not gain it." And my question is how important and dominant CEC is in our CO2 enriched production farms. If we fertilize through the water column does the substrate absorb significant amount of nutrients or is it more like 5% of the consumption? And if it's contribution is low like I suspect it is - what's the benefit of high CEC anyway? I can guess that maybe if we enrich the substrate with sticks then maybe the high CEC shall use them for longer time instead of letting them go straight to the water? Aviel. _______________________________________________ AGA-Member mailing list AGA-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/aga-member