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Discussion Starter · #1 ·
So I've been running slightly higher PO4 (1:6 P:N rather than 1:10) and started to wonder has anyone tried manipulating fert ratios/lighting spectrum to target specific types of growth and developing a staged fertilization system? What I mean by this isn't creating a limiting situation, but having all in excess but manipulating the ratios. A few examples I've thought of:
increasing P:N to encourage root and rhizome growth
increasing K:N and shifting to a redder spectrum to encourage flowering
increasing N+Mg to drive vegetative growth
playing with temperature to see the effects of temperature on red foilage

If so, what ratios were used and how well did it work? What were the drawbacks? What plants were used?

If not, anyone with a couple spare tanks willing to experiment? I'm still getting the hang of basic fertilization in an aquarium but once I do I plan to run some experiments myself.
 

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ive thought about this a lot since i delved into hydroponics and gardening in general long before i got an aquarium. Pretty much all terrestrial plants flower with 10-14hrs of light and grow vegetatively with 15+ hours of light; so having our tanks on 8-10 hour light schedules has always thrown me for a loop as no plant on earth gets that little light, and even then, those are flowering hours and not for vegetative growth. This is all determined by the natural growth cycle of the plants themselves and not something we can alter, I understand the more light = algea, but it just makes sense to give them the same amount of light that they would get in nature, in order to get the proper growth of the plants that is our goal. Much less when we're talking about ferts which also have been proven to have an effect on all terrestrial plants.. why would aquatic plants be any different? especially when most all aquatic species will grow on land.. Im interested in the fert results but have not done any myself yet unfortunately.
 

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So I've been running slightly higher PO4 (1:6 P:N rather than 1:10) and started to wonder has anyone tried manipulating fert ratios/lighting spectrum to target specific types of growth and developing a staged fertilization system? What I mean by this isn't creating a limiting situation, but having all in excess but manipulating the ratios. A few examples I've thought of:
increasing P:N to encourage root and rhizome growth
increasing K:N and shifting to a redder spectrum to encourage flowering
increasing N+Mg to drive vegetative growth
playing with temperature to see the effects of temperature on red foilage

If so, what ratios were used and how well did it work? What were the drawbacks? What plants were used?

If not, anyone with a couple spare tanks willing to experiment? I'm still getting the hang of basic fertilization in an aquarium but once I do I plan to run some experiments myself.
Please read and then re read Liebig's Law of the Minimum.

the ratios do not matter over massive ranges, what do: the absolute individual limiting levels(which is Liebig's point and hence the plank barrel diagram).

This can be extended to aquatic plants and add CO2 gas and light etc......current even etc.

Not just nutrients.

I dose about 5ppm PO4 and 15 ppm of NO3 3x a week, could I do less? sure......but this is a nice ratio for my tanks.. and there's no associated risk of any sort over long long time frames.

In agriculture when you are talking about 22,000 acres of crops, ferts are EXPENSIVE!
Most farmers still lard on the ferts though.......even if you tell them they only need 160lbs per acre of N for such and such crop.
 

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Discussion Starter · #4 ·
Please read and then re read Liebig's Law of the Minimum.

the ratios do not matter over massive ranges, what do: the absolute individual limiting levels(which is Liebig's point and hence the plank barrel diagram).

This can be extended to aquatic plants and add CO2 gas and light etc......current even etc.

Not just nutrients.

I dose about 5ppm PO4 and 15 ppm of NO3 3x a week, could I do less? sure......but this is a nice ratio for my tanks.. and there's no associated risk of any sort over long long time frames.

In agriculture when you are talking about 22,000 acres of crops, ferts are EXPENSIVE!
Most farmers still lard on the ferts though.......even if you tell them they only need 160lbs per acre of N for such and such crop.
Am I misunderstanding that Liebig's Law is merely concerned with the overall rate of growth, and not the form the growth takes? In my mind, the limiting factor in the scenarios I've put forth would be the energy the plant has taken in from the light, and altering the ratios would alter the % of each nutrient taken up by the plants which would drive where they would spend their energy. Maybe I'm mistaken. Plants do take nutrients up indiscriminately as they encounter them, right? And they will spend their energy in the most expedient way, expending the most abundant nutrient first, am I mistaken?

I know this is anecdotal and not controlled at all but when I was dosing .5 ppm PO4, 5 ppm NO3 and 4 ppm K 5x a week with decreasing WCs of 50/25/10 I was seeing a new leaf a day on my anubius. Since switching to 1.2 ppm PO4 7.5 ppm NO3 with K+ being dosed at 4.73 ppm 5x a week+1ppm/day with the same WC and micro schedule I've seen no new leaves but better root growth. . Which is why I want to actually test the nutrient ratios vs form of growth or hear others experiences on the matter.

I was also considering my experience with hydroponics where dosing was done in a 4 part schedule, and lighting was split into 2 stages. I may be mistaken about the dosing in that there were purposeful limitations built in to drive specific growth though as I never delved deep into the individual ferts and simply followed a per-prepared regiment.
 

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If you had a tank with a single plant species in it this might be an interesting thing to try, but with a tank having several species in it I don't see how it could work. Plants vary in their needs so what might have one effect on one species might have a different effect on another.
 
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