hi all, i have to transfer my shoal of Micro rasboras into a smaller tank. what filters have people tried that wont suck them up. i have tried putting coarse foam over the end of my HOB but it cant suck enough water through. I have a spare fluval 2+ but im unsure in they will get sucked up into that. i dont have a spare external and plus its a small 20L tank. any tips or filters that are known to be safe??? cheers.