MTS at water surface

[SPELLBOUND]

Bit worried about my set up. No shrimp yet. But all MTS are near water surface.
Their is a bacteria bloom in a straight line about 4" below surface, not throughout tank, just in a straight line layer.

I am thinking that maybe tank has too much of the bacteria that takes out all the oxygen. But haven't put a filter or air stone in as set it up as advised reading this site.

All my water parameters have been checked twice and come back OK. Just ph a little low at moment at 6.8

Any advice please

[SPELLBOUND]

Thanks that's reassuring, if the MTS die from lack of oxygen I just need to get them out quick

[SPELLBOUND]

[SPELLBOUND]

Put 20 shrimp in today so tiny as think they are babies, lost in this 20 gal. But can see shrimp swimming near surface like MTS, I'm hoping there just chomping on all the biofilm.

Nitrates 0
Nitrites 0
Ph bit low at 7.1