Reddit Ireland has taken the "difficult decision" to shut down in the early hours of the morning, to limit the racist and extremist content posted from the US during daytime hours there.
A multitude of accounts using false identities were to blame, it said.
Moderators said having to check every comment on the group had pushed them to "breaking point".
The page is now seeking to expand its team of moderators and add filters that can spot posts "hateful" comments.
In a post on the page, which has 280,000 members, it said: "We're taking the very difficult decision today to shut down Reddit Ireland temporarily between midnight and 08:00 each day in order to stem the flow of racist/extremist content which is being posted at these times."
"The vast majority of hateful comments submitted over the past while have been solely directed towards someone's skin colour," Reddit Ireland said.
But the filters it would install would also spot "common phrases used against traveller communities and any other minority groups".
Former Reddit chief executive Ellen Pao has said the platform "nurtures and monetises white supremacy and hate all day long".
And co-founder Alexis Ohanian recently resigned from its board of directors, urging the company to replace him with a black candidate.