URLEncode vulnerability - Important

Hi,
I have 2 pages. Page 1 send Querystring value to Page 2 and page 2 use querystring value.
in page 1 I use:         Response.RedirectUrlEncode(("Page2.aspx?q=" &"My Desired Value) )
in Page 2 I Use :        Dim Inputvalue as string = (UrlEncode("request.querystring("q"))
 
I think there is vulnerability in page 2 , and thats when User manally inject some malicious code to address bar.
Now Url is not encoded , but page 2 decode URL. Could any one tell me how to fix it.
 
Regards,
 
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