plants and poo

Both yes and no.

More poo = more N and to a lesser extent, P

However, in order to get more plant growth you also need an appropriate balance of CO2, light and traces.

If in your tank N was limiting, than yes, more poo = more growth. However, I believe that this is seldom the case.
 
If you have just gravel as a substrate then the mulm or poo will help create a soil for rooted plants to grow better in. But as was mentioned it is only one part of growing plants.
 
yes and no, revisited

There is more to poo than nitrate and phosphate. Diana Walstead presented a nice analysis of fish food (and therefore, ultimately, poo), and showed that it has enough of almost every element except carbon for plant demands. Of course, balancing fish output with plant requirements gets tricky.
 
Looks like I repeated what you said, with a few extra words.

In fact, looking at the question again, I think you answered it better. Plant growth is more often limited by light and carbon than N, P or traces.
 
my one gallon plant grow out tank is doing great! i leave it in direct sunlight, it has a clump of hornwort and like 10 baby java ferns, the ferns are growing like crazy

all i have in the tank is 2 femaile guppies and i am feedin them a lot to make them poo al over the place, since java doesnt take nutients in the roots, this shoudl be ok right?
 
Why thanks mogurnda! Much obliged.

Hans, if this is a grow out tank, the plant would have some portion above water right? CO2 is less limiting in the air than in the tanks, namely because it is more available. If I recall correctly, not because of concs. since these are likely higher in a tank even without CO2 injection, but because CO2 can get to the plants more easily.
 
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