I am finally adding some flow to the jungle tonight. Just picked up a nano propeller unit (Hydor Koralia Nano) meant for nano coral tanks that I think will work nicely. It was $25 and has a small propeller instead of the usual impeller style that requires a sponge filter. I really didn't want to fuss with cleaning a filter and worry about shrimplets getting sucked in. It's a pretty slick lil unit that I can rotate it to direct the flow in any direction and I think I'll adjust the flow every other day to give some variation. It also fits in with my low consumption ideology for the tank, as it doesn't take much power to drive it.
Those with flow in their tanks, do you think I should cycle the flow on/off with the lights? Or just leave it on all the time? I'm worried that if I leave it off and then turn it on in the morning, there might be shrimp or snails that will climb into the unit and either get crunched up or damage the unit.
Should I place the pump high or low? Do I aim the flow straight across or angle it up/down? I plan to experiment but wanted to know if there are any advantages to flow direction or placement.
I think the guppies will like it, as they are always dashing into the stream when I fill the tank.
I have 3 and love them. I leave mine on all the time. On my 40Bs, I have a small HOB on one side in the corner and I place the Koralia unit on the opposite corner to help the water move around the tank. These are placed so that the flow goes straight across the top. Between the filter and the Koralia I can see a slight circular pattern in the water movement.
On my 75 gal, again I place the Koralia unit opposite the spray bar, but I position it in the upper front corner. The flow is directed towards the opposite back corner and I have it tilted at more of a downward angle.
It's all experiment to see what works best for you. Stick it in, see how the water moves and adjust depending on your situation.