20 Gallon for plants/fish/shrimp
I setup this tank a 20 gallon high to harbor shrimp and fish. In the first photo you can see that plants are growing in the foreground for a fish refuge while at the far end there is a sloping rock shelf with caves in the rear for the shrimp to hide.
This rock shelf is directly below the filter outlet and most of the filtered water flows down the shelf towards the front center of the tank. The flow at substrate level is strong enough to discourage the foreground plants and a gap in the bottom plant cover is visible.
A small part of the filters output circulates around the rear of the rock shelf and flushes the several caves/ledges inhabited by the shrimp.
The tank is in a position where it receives oblique sunlight through the planted end for a couple of hours every day. This coupled with the 65 watt T5-HO lamp makes for lush plant growth.
At this time there are about 25 Cherry Shrimp who are reproducing and 12 Ghost Shrimp. Most of the invertebrate activity occurs after lights out but occasionally a Ghost or Cherry Shrimp goes for a walk under the light. Surprisingly they are ignored by the fish and seem to wander around without any fear at all.
I test the Ammonia Level every 2 days and there has never been a spike since I set the tank up. It seems that the plants are doing there jobs. PH this morning (11/26/2010 was 6.8/6.9