Alerting low disk space

Hello. I`m trying to create monitor that will send notifications about low disk space
This query works fine
{
“query”: {
“bool”: {
“must”: [
{
“range”: {
“system.filesystem.used.pct”: {
“gte”: 0
}
}
},
{
“range”: {
@timestamp”: {
“gte”: “now-5m”,
“lte”: “now”
}
}
}
]
}
}
}

but when Im trying to change "range": { "system.filesystem.used.pct": { "gte": 0 from 0 to 0.5 its stop working :frowning:
In logs I can see system.filesystem.used.pct
0.521
0.702

Can anyone help? I`m already trying to double quote “0.5”