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[APD] Re: Sub N
>I wonder if another variable here may be how the plant was grown. Would the
>plant develop differently if it is grown with a significant substrate N
>source(and potentially deficient water column N) than with an essentially N
>free substrate or a substrate with N concentrations similar to the water column.
>just a thought.
This was shown as a larger amount (dry weight biomass) than the control(rich sub and water column) in several studies.
If a plant does not have to expend root growth to get nutrients, why would it?
I would be alazy plant too given a choice........the problem is when folks do not give the plants a choice nor remember to supply the nutrients back.
Soil, sub ferts etc all run out at some point and you need to add more.
Water column ferts permeate the substrate as well(and vice versa).
So you gain no algal relief from that method.
Anyone that does heavy water column ferts with no macro's in the substrate can see the effects on so called "heavy root feeder" like crypts and sword plants.
They do better in water column fert routines and grow better.
They do not "prefer" root ferts, this is a myth. It's just most folks have deficicent water column ferts so when they add a jobes etc, the plants do perk up. If you have enough experience and watch the plants, add the water column ferts, this is fairly obvious.
I have no trouble with any so called heavy root feeder or any plant for that matter. I have not dose the substrate for a very long time except in a few test tanks and I've had about every available sword and Crypt.
It is typically a lack of something, more than were you put the fert's that's the issue.
Given a choice, the plants will go for the water column source if there's enough.
There might a plant out there that takes in one or more nutrient more but I am not aware of any. As far as a generalization, plants prefer water column.
Am I against adding substrate macros?
Nope, but I think adding both is not a bad idea with more critical weight being placed on the water column.
Less so on the substrate, but you can make the sub your primary method if you want and have lower light, less uprooting/replanting/moving of plants. Try non CO2 if you like that method so much. Each method has it's trade offs. There is no perfect method for everyone and certainly not for me.
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