Help with 1 week old 10g nano

[Nixon]

Pieces has this generic one that plugs into the rio (aquaclear i believe). I just can't figure out how to get it to float and adapt as the water level changes due to evaporation. it was something like $17.99. Pretty cheap but I guess you get what you pay for. Let me know if you end up getting the same one and if you get it working properly. I have an elastic holding the top piece down and just setting it to 100% surface skim instead of 50/50 surface/underwater.