How long can i hold a Margin Position before it is closed?

>>3420239
on the site I use I have to cover 50% of my input, so if I use 100 dollars of my own I need atleast 50 personal worth.

>>3420280
yes, (i use bitfinex) but how LONG can i hold a position.

I think it was 28 days on Bitfinex, but don't quote me on it. Someone in /biz/ was recently liquidated and found out the hard way.

>>3420280
So is it:
> put 50 in the kitty
> 25 goes in, 25 spare for margin calls