[APD] Re: Are sword root feeders?

[Thomas Barr <tcbiii at earthlink_net>]

"I am curious: do most people have to fertilize their Echinodorus' roots?
Several people here suggest that plants can get everything they need from
the water column. Is this not true for Echinodorus spp.?
Or is the issue that my substrate is too fine to allow the 40 ppm of NO3
from the water to percolate down to where the roots are?
I'm just surprised to hear that some plants *can't* get everything they need
from the water column, and would like to hear others' experiences on this
point.

- Jim S."

I'm going to straight you out here.

Please name one submersed aquatic rooted plant that cannot get EVERYTHING from the water column. 
I'll take anyone on about this issue.

I've had huge monsterous Swords for years in RFUG's with no substrate ferts.
Swords and Crypts have well developed root systems, but they do not prefer root uptake anymore than other plants. Their habitat is often variable and lotic(moving), anchorage is important. A wimpy roots system send the plant downstream.  

While they can get a lot of nutrients from the substrate and will when the water column is limiting, I've grown some 200 species of plants in RFUG and used only the water column to grow them.

Folks say they prefer "root feeding" for some reason, but they are generally repeating(nothing against Dave here)  previously held myths or have not looked into sediment uptake or done their own experimenting and control with the water column.

The last thing I want is a sword because they get too large in my tanks way too fast. I do nothing for them as far root feeding.

Looking at your info more carefully, I'd say you have a NO3 limitation. Don't trust the kit. 
As the sword plant gets large and large, it will now need more and more "food".

So you can trim the weed back or let it grow and start adding more nutrients.
Low bioload non CO2 tanks need KNO3 and sometimes PO4, most can handle no trace additions.

After a year, it sounds like the sword has sucked all the N from the substrate.
You can add KNO3 or add more mud cubes aroud the base or a jobes etc.
You can also add more fish or add more fish food etc.

While you can get good growth from most plants with substrate fertilization methods, they will do equally well with the water column or better. A good plan is having both in case the test kit is wrong or you forget etc.

But are they mandatory root feeders and need rich substrates?

No way. Same for Crypts and Aponogetons, Lace plants etc. 

Regards, 
Tom Barr



 






 
  
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