Vinegar dosing, what's on the sand?

[Aquaph8]

I've been dosing vinegar for quite a few years now and have always had what I always thought was diatoms. A few months ago I decided to stop dosing just to see how my tank would do without it and to my surprise it's really hasn't changed too much nitrate wise. I do have a little more PO4 according to tests but not too much.

What really surprised me though was that after I stopped dosing the so called diatoms vanished and for the first time in years I have a nice white sand bed. Was the mystery brown dusting on my sand bed actually bacteria bloom? If I decide to dose again in the future can I keep this bloom in control by dosing less? Was the issue caused by dosing too much? I never really felt like I was dosing too much by how the corals reacted, my SPS were never really pale at all.

 

[Randy Holmes-Farley Verified Community Expert]

I'm not sure. It might have been bacteria, or if you have enough silicate, perhaps the diatoms were consuming vinegar.