20L flow issues

[Reygan2]

I have 2 Koralia 425's and a 240. I have tried using various combinations of these to create a nice flow, but regardless of how I position them, one or more of my corals end up getting too much flow. I am at a loss as to what to do. I am running an AC 70, but I switched the impeller with an AC30 so the flow is reduced, but it still creates quite a bit. My main problem is my sand bed stays covered with algae, possibly diatoms but not sure. I'm thinking that better flow would help. Right now I have one K240 on the right side facing the back of the tank, which is creating some flow, but not helping my sand bed at all. When I face it towards the middle of the tank my mushrooms and frogspawn take a beating. Any suggestions on which pumps I should use or where to put them?

 

[Sillywilly]

I also am running a 20L with 2 425's , a 250 and an AV 70. I have a 425 on the left and the 250 on the right. I have them at the same level about 3 inches from the top of the tank. I have them in front of the tank. I have a grape coral on the right side under the 250 and it seems to be doing fine with the current. I have the other 425 above the 250 on the right. I only use the extra 425 at night and turn if off in the morning to switch up the flow.

 

[Reygan2]

What type of scape do you have? Do you have corals?

 

[Sillywilly]

My rock scape runs the entire width of the tank with one cave on the left. I have a few zoa frags, poly frags, Duncan frag, grape coral, plate coral, a few leathers, sps corals and just got a Xenia frag.

 

[Reygan2]

I haven't tried putting them in the front. Good idea.