Substrate recommendations please

[wes.crockett]

Hey all, 

Working on migrating my 10g and 2.5g tanks to a new 35g cube. The cube will have a cave feature that sits about 4" tall so I need the substrate of the tank to be at least that deep. I'm OK with a deep substrate since the tank itself is so tall. I plan to have Fluval Stratum in the substrate as a layer, and I have about 35lbs of it (2 bags). That alone won't be tall enough, I think, so I plan to do some form of pebble/gravel/something on top of it, but not very deep.

For a height-adding layer, what would you recommend UNDER the Stratum layer and, importantly, how thick would you go with the Stratum.

My 2.5g planted tank is an algae nightmare and I believe it has a lot to do with the sheer amount of Stratum-to-water ratio since it also has the cave feature making the substrate height fairly high.

[Fish Folk]

I’m an advocate for black Activ-Flora. 

[Silverback]

When I'm looking to add some height I like using media bags filled with small lava rock bought from a home store.  I use media bags that plant roots can easily grow into.  I'll stack them on top of each other and then cover them with the media I'm using.  If I ever break down the tank or change substrate I don't have to worry about them mixing.