Help with coding a macro

Below I have this marco the goes from row 2 to 2000(and that's okay), but I don't want to have to later in the year go and update this macor because it has exceed 2000 rows.
How can I put something like Range(Selection, Selection.End(xlDown)).Select, which goes to last record in place of 2 to 2000?

Sub col_n_check()

    Dim curr_Row As String
    For i = 2 To 2000
    If ActiveSheet.Range("BV" & i).Value < 0.3 Or ActiveSheet.Range("BW" & i).Value < 0.3 Or ActiveSheet.Range("BX" & i).Value < 0.6 Then
    curr_Row = i & ":" & i
    ActiveSheet.Range(curr_Row).Interior.ColorIndex = 24
    ActiveSheet.Range(curr_Row).Interior.Pattern = xlSolid
    End If
    Next i

End Sub

Keeps giving me a syntax error.

Sub col_n_check()

    Dim curr_Row As String
    For i = Range("Bw2:Bw" & Rows.Count).End(xlUp).Row
    If ActiveSheet.Range("BV" & i).Value < 0.3 Or ActiveSheet.Range("BW" & i).Value < 0.3 Or ActiveSheet.Range("BX" & i).Value < 0.6 Then
    curr_Row = i & ":" & i
    ActiveSheet.Range(curr_Row).Interior.ColorIndex = 24
    ActiveSheet.Range(curr_Row).Interior.Pattern = xlSolid
    End If
    Next i

End Sub

@ mike7952,

Thank you for helping out here Mike,

I was just going to ask for a sample WorkBook to see what the heck is going on. I have also slipped up badly by excluding the "2 To" bit.

I worked some. It just didn't go all the way to the bottom of the page. I have 280 rows and it stopped on row 23.

Sub col_n_check()

    Dim curr_Row As String
    For i = 2 To Cells(Rows.Count, "B").End(xlUp).Row
    If ActiveSheet.Range("BV" & i).Value < 0.3 Or ActiveSheet.Range("BW" & i).Value < 0.3 Or ActiveSheet.Range("BX" & i).Value < 0.6 Then
    curr_Row = i & ":" & i
    ActiveSheet.Range("a" & i).EntireRow.Interior.ColorIndex = 2
    ActiveSheet.Range(curr_Row).Interior.ColorIndex = 24
    ActiveSheet.Range(curr_Row).Interior.Pattern = xlSolid
    End If
    Next i

End Sub

Okay here is the stange thing. I was making you an example copy to look at and the macro works fine. It goes all the way to the bottom. But, in my actual sheet it only goes to 23. What should I be looking for? I'll keep playing with it.

Fixed it. There was a #DIV/0 in column BV. So, made the formula an iferror..... Works fine. Thank you so much for your help. This is awesome. I apologize for it taking so long.