trying to make milk kefir grainy texture and what to do if separates to curds and whey for some reason

hi new to kefir making
just wondering why does it have a gritty grainy texture?
how do you stop that ??
and also i put on table for 2 days ( about 1/2 tbsp grains in 500 ml milk ) in glass jar with paper lid with rubber band and it separated in to what i presume is curds and with liquid whey at the bottom...?
what are you supposed to do with it if it does that?
also the actual curdy part is full of little lumps.. like not smooth.. i strain the curds and whey through sieve and
gritty ..
im a newby to this so any tips how to make smooth tingly yummy kefir would be appreciated .. i am in a not that hot climate but summer at moment so room about 15 c or 60 degrees ..
i assume i am not supposed to have curd whey thing happen. would like it to remain yoghurt!! any ideas how to keep it right??
TY in advance
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