Maybe we could get the OP to tell us more about what prompts them to ask the question?
It’s not about eliminating the biofilter. It’s about providing as much NH4 as the plants will take up, rather than relying mainly upon NO3. The ultimate goal is to find out if there will be a noticeable difference in plant health without harming the fish.
Since plants seem to prefer NH4 to NO3, I was thinking; why not let the plants eat before the BB without having to add ammonium as a supplement? I suspect, in the end, that I will just find a greatly reduced (optimized?) level of bio media. Right now, I fill the filter basket with Matrix figuring the more the better. Now, I’m wondering if less (maybe none) is better by providing only enough nitrifying media to keep NO3 at a very low level, which, in my case, would be less than 5 ppm. I know that NO3 levels in the 20-40 ppm are harmless, but it says to me that all that ammonia is being used unproductively from a plant perspective.
At my pH levels of 6.0-7.0 (CO2 day/night variability), the NH3 should almost instantly be converted to NH4. So, while I’m not too concerned about NH3 or NO2 spikes (which I will still monitor), I am concerned about determining if unlimited nitrogen is being sustained. I’d rather not wait for deficiencies to develop, which could cause a downward cascade by that time. So, I’m going to watch for changes in phosphates (now in the 5 ppm area) assuming that a drift higher means plants are limited by something (nitrogen in this case) or assuming that a drift lower means plants are becoming healthier and the non-nitrogen nutrients are becoming limited. That, when combined with total ammonia testing (while trying to keep free ammonia near zero), may help show me the point of balance.
Things to watch (I’m sure ither thoughts will pop-up along the way):
- When photyosynthesis stops at night, will it create a problem
- Will the tank be more/less prone to algae.
Who knows where this is going to end, but I have plenty of Prime and zeolite on hand that could be employed while I rebuild the BB colony, if needed.
Can I ask how the OP came to be using the Matrix?
I selected Matrix as the bio-filter media simply because it is renown for being a high-quality porous media. I’ve been using it for about 15 years, maybe more.
The above three posts give me added confidence that I can remove most, if not all, filter media and may actually have answered my initial question.
I do have a question for the three of you: do you have total ammonia (not free ammonia) testing levels above zero? That might indicate that the ammonium that plants like is being made available.