# Purpose of specialty substrate?



## MikeWinLDS (Mar 29, 2004)

What's the purpose behind using specialty substrate like Eco-Complete, Onyx Sand, Fluorite, Laterite, etc. Maybe try to explain in terms anyone can just pick up, read, and understand. Don't need to be too techie. Don't just say, "It's good for plants," and end either. Why or how, that's what I'm talking about. TIA.


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## Sir_BlackhOle (Jan 25, 2004)

A lot of them contain elements like iron that the plants can use. They also usually have a high cec, which i think means that they can hold on to elements that the plants can then absorb throught their roots. They are all supposed to be beneficial to plant growth because of these reasons. There may be more that im missing.


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## MikeWinLDS (Mar 29, 2004)

Does the Iron fade away over time then if plants keep "eating" it? And what is CEC?


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## Sir_BlackhOle (Jan 25, 2004)

CEC is cation exchange capacity. Something to do with positive elements being cations, and a high cec means it can hold more elements. 

Yes I think that eventually the substrate can be depleted of iron, but im pretty sure that that will take a long long time. Hopefully someone with a bit more knowledge will chime in here soon.


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## SCMurphy (Jan 28, 2004)

The point is to bilk you out of your hard earned money. There isn't any reason for these substrates to cost more than $10 a bag other than shipping costs, and paying the guy that designed the art work for the bag.


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## cS (Jan 27, 2004)

For a planted tank, an ideal substrate system should be inert, exhibit micro/macro porosity, and contain all macro/secondary/micronutrients. Since all these features are not currently available in any one substrate system, we go for the next best thing: inert, porous, and high in iron. Inert because we don't want it to interfere with the water chemistry. Porous (CEC) because it promotes healthy root growth as well as provide a reducing environment in which certain nutrients are made available to plants. High in Fe because it is one of the nutrients that is beneficial to be present in both the water column and substrate.

Aside from the above utilitarian attributes, there are other factors to consider like color, how easily it cloud the water column, cost, etc. Eco-Complete has been so well praised because it accomplishes many of these criteria, but is quite cost prohibitive. It does not mean that if you don't have Eco-Complete or any of these commercial substrates, then you can't have a well running tank. Speaking as someone who live in the United States, we have so many choices available nowadays for all sorts of price ranges that IMHO, no tank should be grown in plain gravel or sand...unless you have some odd affinity to them. :mrgreen:

Keep in mind that the substrate is one of the more permanent features in many of our tanks so an initial well-chosen subtrate system will save you a lot of heaches later on down the road. Speaking from experience, changing/modifying the substrate system is a HUGE hassle.


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