No,no,no!Please don't buy any more chemical products, it's money down the drain and would be better spent getting a bigger tank off eBay. You're trying to fix a bleeding wound by bandaging it rather than doing what you should be doing which is stitching the wound.
Thanks for all the help

Again thank you very much, in furture when I buy fish I come here for advice and not leave it up to the retail stores.
Last question, what size tank would be resemble for three goldfish & a pleco?