private int findFreeId() {
		for (int i=vortexSpaces.length-1; i>=0; i--) {
			if (vortexSpaces[i] == null) { //check if null's have to be put
				return i;
			}
		}
		
		int onGoingId = vortexSpaces.length;
		doubleSize();
		
		return onGoingId;
	}