I have an ACII and Aquanotes 3, as well as a DC4. I like the Aquanotes in that it gives me a better interface with the ACII, but with the embedded web server in the AC3Pro, I would think it would no longer be necessary. About the only other thing I use it for is to graph data (temp, pH, ORP, etc) which the embedded software in the AC3Pro won't do. Overall, considering the price of Aquanotes, I don't think its a worthwhile investment, esp it you're getting the AC3