Help making a river bed.....

[londonloco]

I'm planning my 75g rescape, and I want to make a riverbed. Mineralized Top Soil capped w/a combo of left over black flourite, 3m quartz and Seachem black sand will be the substrate used for where the plants grow. But I want to put a riverbed with no plants, probably using some sort of tan or off white sand. How do I keep the substrates separated and keep plant runners from encroaching in the river bed? I know I've seen some tanks that have done this, I can't remember how it was done. Thanks!

[krisw]

You could use plastic acryllic sheets (like overhead projector sheets), cut into strips and placed below the substrate line. Then, use rocks/plants to hide the plastic, which should already blend in pretty well. Bottom line, however, there's going to be some mixing of substrates that's unavoidable. Also, the tan/white sand will get algae on it, so buy extra, as you'll occasionally need to siphon off the top layer, and replace it with new clean sand.

[londonloco]

Thanks Kris. Why I have never had light substrate in a freshwater tank, didn't want to deal with replacing when it got all "gunked" up. Hmmmm, thinking of maybe using a similar color, but larger size substrate for the river bed, like larger gravel. Maybe different textures would give the illusion of a river bed?