Originally Posted by Molinious
The tank i have is 2ft wide so witdh wouldnt be a problem, maybe some cichilids might like it, a 200ltr an hour filter without a spray bar would produce enough of a current, as said below a smaller fileter of maybe 1000lph with a spray bar would complete the circulation. The only problem i can think of for a strong current is the wave you would surely get, being only 4ft long it soon build up
Wave? you can't generate much of a wave on the end wall, which is partly why I suggested the midstream rock blast... puts any wave in the middle and slows down the current toward the end anyway.
I don't think that 2' is wide enough, the sections would be too small... 36" would be better and square better yet... but you already have a tank. What you will end up with will basically be a large swirl and you won't have a stillwater area, not enough width to let the flow slow down in a wider area so the effect will not be fast water/slow water divided. You won't be happy with the result.
Having said that, perhaps a split is still a good idea, go side by side instead, skip the fast water idea and create a rocky side and sand side with a variety of plants and vertical flat rocks to provide a visual and ecological division. On the rock side you could go with a small waterfall (just flow some water over the rocks, not really a waterfall, that might get too annoying to listen to) and a scattering of grass like plants between the rocks, on the sand side, surface plants, stems and carpet plants, maybe some wood. Similar idea with the fish but you don't need to deal with fast water fish... just rock preferring and sand preferring.
The downside is that you would have to consider each side as the "tank size" when considering fish even though the bioloading is for the tank as a whole which may limit you to slightly smaller fish than you may have preferred with a wide open tank. The upside, more fish overall.