What does... mean?

mhhauser

mhhauser

Sup
Jan 10, 2006
23
0
0
Ohio
Latley I have been reading up on planting a aquarium, and I was getting kinda of curious what the term


"CEC"

if you don't know it here is it being used in context

Zeolite - any of various hydrous silicates of aluminum that are analogous in compostion to the feldspars. Contains either sodium or calcium or both of the type Na2O2.Al2O3.xSiO2.xH2O. Can act as ion-exchangers. Has high CEC

any help
 
CEC references the ability of certain minerals to hold positively charged ions (= cations) on their surface structure. There may be some serious implications of this phenomena in substrates, or it may be trivial, or most likely it can help a bit make cations of micronutrients and macronutrients more readily available to root hairs of plants, but also most likely it is not of major importance.

In recent years this particular flag has waved a lot around the planted tank communities, but rather like the even earlier PMDD theory, it turns out to be not quite right and certainly not of major importance. Some very successful substrates have high CEC. Other equally successful substrates do not. Therefore the rational conclusion is that the CEC is not and should be a major factor in substrate selection.
 
In very simple terms. It is the ability of a substrate to trap, hold, absorb, adsorb nutrients which are/can be available to plant roots.

Flourite for example is a porous fracted clay that has a high CEC rating.
Polished or epoxy coated stone type substrates have a low CEC rating.

Jay

RTR is right on!
 
I am curious about your aside re PMDD -- I thought this was a reasonable way to dose chemicals for plants -- or is that outdated now??
 
PMDD was based on limiting nutrients for algae suppression, especially phosphate. That turns out not to work. Phosphate is macronutrient and absolutely required for plants. It was a nice theory and can help with low light slow growth tanks, but its theoretical basis is incorrect, and in moderate to high light light tanks with CO2 (bioavailable carbon) supplement it will promote algae more than supress it.

Tom Barr's concept of taking care of the plant's needs first and foremost works a lot better IME. In lab-speak, it is a more "elegant" concept - if you want higher plants, provide for their needs first, then control excesses by the simplest technique available.
 
Nod nod.

I have a lot of phosphates in my tap water and use *some* Phos-Guard in my 65g. Just enough that there are some phosphates, between .5 and 1.0. I don't want to wipe them all out.

It's tall (24"), low light, no CO2 and mostly low light plants. A few high light ones, but they're directly under the lighting and doing pretty well.

There's hardly any algae and I'm having to support the SAEs with algae wafers to make them happy. Plants are growing good and I'm adding ferts as well.

I wouldn't dream of using phosphate remover in my other tanks.

Roan
 
You must log in or register to reply here.
AquariaCentral.com
Top Bottom