It is not all that complex. For a start, most equipment for tanks doesn't draw that much power. Heathers are the biggest users. Lights these days tend to be lower power as well. So here is what you can do to "eyeball things. Every piece of equipment has specs which includes how many watts are used. Filters, pumps, heaters etc. are all rated this way as well as others. You can use this information to determine how many amps are involved. Fuses and circuit breakers are rate in amps.
It is easy to add up all the wattages involved. What you will discover is they may be less than what you believed. Heaters are easy as they are bought in watts. The other stuff you have to look at to get the watts, but here are a few examples:
200 gph AquaClear hang on uses 6 watts, their 500 gph uses 14 watts.
An Eheim Pro 3canister good for up to a 92 gal tanks uses 16 watts.
A Mag Drive 950 gph pump uses 93 watts.
So what you should do is to calculate what total amps your setups need. Most home circuits are 20 amps. This is easy to do using the online calculator here: http://www.supercircuits.com/resources/tools/volts-watts-amps-converter
1. Find the wattages of all the equipment involved.
2. Plug the following info into the calculator. Your Volts are 120, your watts are what you add up for your equipment and then you can find the amps.
3. Calculate everything else on the same circuit and add the two things together and you will know to the amp if you are exceeding the circuit(s) you are using.
Here is what I can tell you re my setups. I have tanks in three rooms which involves two 20 amp circuits. In addition to the tanks there are televisions, cable boxes, a computer and screen as well a UPS and cable boxes. I currently have 15 tanks from 5.5 to 150 gals on these two circuits. Most tanks have 2 or 3 filters,many have 2 heaters and about 1/2 run lights for part of the day. I have never had a problem. I run air pumps, power heads, small pumps, hang ons, canisters and assorted lights.
I also have a couple of power strips chained in pairs. I do this when short of wall plug space. I see no problem with this as I have seen plenty of setups with custom strips that have even more capacity for plugs than the 11 my chaining gives me. I have never chained more than two however and the strips I use are heavy duty, grounded (3 wire) and have a circuit breaker built in. Many people will suggest it is a good idea to use initial receptacles with ground fault interruption built in. The kind typically used in bathrooms or kitchens.
Hope this helps.