Från Flourish Excel Support:
http://www.seachem.com/support/FAQs/FlourishExcel_faq.html
"Q...When I first dosed my tank with all the Flourish products I was experienceing quite a bit of hair alage. (125gal plants/fish) Within three days the hair alage had turned a reddish orange and about four days after that it had completely disappeared.
A The experience you had was due to using the Flourish Excel. We found that to be an added perk of the product. We do not recommend to overdose the product but you can adjust the amount dosed and frequency of dosing based on your personal results.
Q Q: Is Flourish Excel a replacement for CO2 in a planted aquarium?
A: Yes and no. It provides the same benefit as CO2, i.e. it provides the plants with a source of carbon for growth just as CO2 provides them with carbon. However CO2 by itself will give you quantitatively more growth than Excel by itself, although Excel does provide a substantial amount in comparison. If CO2 is a 10, Excel is a 6-7. Using both together provides additional benefit. One of the advantages of the Excel is no up front equipment costs and complexity of valves, hoses and regulators, etc."
<<<(^:>*