Substrate - mixed or layered

[RubiconRider]

Hey there,
I am going to replace my pebble substrate with Eco complete.
This is my first tank with live plants and I want to experiment with different plants and figure I'll be more succesful with the Eco complete.
I also really like the look of the black sand I've seen for sale at Big Al's.
So I was thinking of putting down 2" of eco complete and one inch of the black sand on top.
Good idea? bad idea? why?
Should I mix them together instead? why or why not?
My tank bottom is approx 36" x 18"
Is there a formula to calculate how much substrate I need to buy?
Every other tank I ever set up had an undergravel filter.
Is this a no no for a planted tank?
Finally, I want to keep as many fish as I can in the tank.
I am use to vacuuming the gravel when I do weekly water changes.
But while reading through this forum I never hear of any one vacuuming their planted tanks...why not?
Thanks in advance.

 

[lucas68]

Should I mix them together instead? why or why not?

They tend to get mixed all on their own.

Every other tank I ever set up had an undergravel filter.
Is this a no no for a planted tank?

I don’t think the UGF will get along with the plants roots, but if you like it, good luck.

I am use to vacuuming the gravel when I do weekly water changes.
But while reading through this forum I never hear of any one vacuuming their planted tanks...why not?

I vacuum my tanks every week. Ok, I try to do it every week. When I vacuum, I just try to be careful not to disturb the plants. This why everything gets mixed together in my substrate.
I hope this helps.

 

[RubiconRider]

Thanks

 

[jart]

Go to plantedtank.net for a substrate calculator to find out how much you need.

Most plant folks prefer cannister filters. You can consider HOB; if you inject CO2 consider some foam on the outlet to minimize surface agitation. Wouldn't the sand fall through the UGF grid?

If you are new to planted tanks read everything here: www.rexgrigg.com.