TLDR My geoJSON layer will display the vector mark but will not destroy the features or re add the features in causing a moving / updating look to the OpenLayers map.

Hey S O. I have a geojson layer set up as follows:

//GeoJSON Layer//
var layer1 = new OpenLayers.Layer.GML("My GeoJSON Layer", "coordinates", 
             {format: OpenLayers.Format.GeoJSON,
             styleMap: style_red}); 

My features are set up as follows:

 var f = new OpenLayers.Feature.Vector(null,style_red);         
 var style_red = OpenLayers.Util.extend({}, layer_style);
 style_red.strokeColor = "red";
 style_red.fillColor = "black";
 style_red.fillOpacity = 0.5;
 style_red.graphicName = "circle";
 style_red.pointRadius = 3.8;
 style_red.strokeWidth = 2;
 style_red.strokeLinecap = "butt";

and my layer updating function:

function UpdateLayer(){
    var p = new OpenLayers.Format.GeoJSON({
                 'internalProjection': new OpenLayers.Projection("EPSG:900913"),
                 'externalProjection': new OpenLayers.Projection("EPSG:4326")
            });

    var url = "coordinates.geojson";
    OpenLayers.loadURL(url, {}, null, function(r) {
        var f = p.read(r.responseText);
        map.layers[1].destroyFeatures();
        map.layers[1].addFeatures(f);
    });

    setTimeout("UpdateLayer()",1000)  
 }

Any idea what I am doing wrong or what I am missing?