FWIW -
The most common mistake a person can make in starting a small business is not understanding the cost of doing business, and whether the proposed income can support the costs.
While it's important to know what other maintanence companies charge in other parts of the country, it is much more important to know what your competitors charge and what they provide in services.
I'd suggest a basic business plan that defines your objectives and lists the costs you will regularly encounter such as transportation, supplies (Test kits, RO DI water, salt, etc.), marketing, taxes and the like. Once you have determined your costs, does the income you plan to make cover the costs and leave you enough left for a wage.
I realize that you probabaly know this info already, but I've seen more than my share of individuals believe that since they can maintain tanks that they should start their own maintanence company. Unfortunately, few succeed because of their inability to run a business.
If you have a passion and are willing to mind the details, you'll be successful.
I may not have answered your question, but I hope this helps.
Spinner