Water

Please help i set up a 50g reef aquarium an the cycling has began rocks an sand are covered with diatoms an there is no ammonia in the tank an nitrates an nitrites are at stable conditions , the only thing that is making me worried is the water at the top of the tank its hard to describe what it is but its like a bubble type at the top if you have any idea what this could be please let me know

 

if you have a lot of water movement or flow in the tank
then your aquarium is acting like a protien skimmer whilst cycling
the agitated water, and bubbles created by that water movement, collect protiens
and they are then held on the water surface by surface tension

when you do your 1st water change after cycling
use a plastic jug or bowl, place it gently into the aquarium, allowing this collected froth to spill into it

additionally - a paper towel placed gently on the water surface will cause this froth/ foam to stick to it, and you can remove it in that manner