Does plant roots work as biomedia?

[Usman]

Hi , i was wondering to which extent plant roots work as bio media and if not then what can be reason.... can we have a pond with just alot of plants as filter system . what are the disadvantages of having alot of plants ?

 

[Jhn]

Plants are the 1a filter system in my pond. I do have a skimmer/waterfall system which would be 1b, but it only turns my 10,000 gal. pond over once an hour. Probably 75% of my pond has plant coverage. The only disadvantage to me of having alot of plants is if you don't like to get in the pond to trim back the excess growth. The key for me is having plants that spread aggressively and uptake a lot of nutrients, i.e. water celery, parrot feather, pickerel rush. I am constantly "weeding" these plants back in my pond.

 

[MitchM]

Biofilms form on submerged surfaces because that's where nutrients will collect.
Nutrients collect on submerged surfaces because submerged surfaces have a negative charge and attract positively charged cations and dissolved organic carbon (DOC) (ammonium is a cation)
Plant roots are feeding off these same nutrients, so there won't be a strong biofilm develop on plant roots.

The only limitation to having a lot of plants is the availability of nutrients for the plants to feed off of.

 

[Meyer Jordan]

Periphyton also grows on all submerged surfaces including any submerged portion of an aquatic plant. This only augments the N assimilation that is already taking place by the plants themselves. This is the process that makes wetland filters ('bogs') so efficient in nutrient reduction.