what smells so bad????

[saltman1120]

ya it alomost is like a rotten milk smell. also i only see they cyno on the rocks and on the bottom when the lights come on. when they are off i can look with a flashlight and it isnt there. and it only out in the open light not behind or underneth the rocks. why is it that the bubbles from my skimmer only sticks to the rocks and stuff when the lights come on too. what is it with the lights?? its weird!

 

[saltman1120]

what do you think about 2 hydor koralia power heads 400 gph each. what should i consider for skimmer for hang on the back but with low microbubbles returning in the tank? i was gonna get a 20 gal wet/dry filter with skimmer and everything in it but im not sure what to get????? so many differant opinions, dont no what would be better, even if i decide to go to a 60 or 75 gal.