#equipment help

Hey all I’m new to saltwater and my friend has moved away so we had his tank and his live rock (around 4kg plus some ocean rock). Everything seems to be going smoothly minus bits on the surface? I’m worried that my water is not getting enough oxygen. Ph is 7.8, Ammonia, nitrite and nitrate all...

So I can’t stop my petite in skimmer from producing micro bubbles that then feed into my return, I’ve tried adjusting the setting on it but that dosent work.Any suggestions? By the way this isn’t a new skimmer I’ve had it for over a year and only after I put it in my new setups dose it do this.

I just need some help figuring this out, on brs I see that some UV sterlizers are 25w but 450$ while others are 25$ but for 250$.I’ve read through them and see no differences so I just need someone to tell me their oppions in what I should do