Hello,
I run an aquarium maintenance service so maybe I can help.
I love money but not at the point to exagerate the need for maintenance. usually, for the first month, I do some weekly visit just to have a look to the system and make sure everything is fine. After that I visit my clients twice a month. At each visit I test the water, make some adjustment if needed, check the equipment, inspect corals and fish and do a water change.
What I hate the most is that most of my clients made the setup and called me for maintenance after. What happen the most is that the system can't hold that much live stock so I work more for less result. When I do the set-up I make sure it's gona hold as much live stock as needed.
price can be quite different from a place to an other. Does he have competition? is the average income high or low in your region? All this can make the price change.
Where I am, I have no competition and the average income is quite high. My cost for a salt water tank goes like this: $50.00 + 0.50/gallon ($100 min). This include a complete maintenance routine but does not include supply of additives.
My cost might be high or low depending on where you are. For sure, it can be quite expensive with time but it's a good deall for someone who want's a nice reef tank in the office and don't want to touch it.
Also, I would be curious to know how much they charge you for that.