Gotta go with thrak here. Does your land lord understand that a 55g tank is 440lbs of water alone? So even with the reduced number of tanks it is almost 3,000lbs of WATER alone. (assuming you have 3 20g tanks). So add the substrate, decor, equipment, and so on. My 29g tank alone, just the tank is about 30lbs. I am guessing some of your tanks will be glass, and some will be acrylic.
You need to explain this weight to your land lord. Most people dont even think about the weight when they think of fish tanks. Heck, even I didnt think of the weight of my 29 until I got around to needing a stand for it. Another thing to consider is noise. There is no way you will get all of those tanks to be quiet. Each one needs its own little adjustments and need to be topped off even if it isnt time for a water change. You also have to think about smell. I know that some tanks grow algae and stuff and it will begin to smell like a lake. I dont know how hard it is to get rid of that smell, but it wouldnt be enjoyable when it is time to get rid of it.
She will also need to think about the electricity required to run it all. Sure the filters dont need much, in fact most are less than a light bulb. But you have to add up all of the heaters, filters, lighting, air pumps, and so on. You will want high quality outlets that are properly grounded, and you should probably add a separate breaker for the room. Some electricians will charge a lot to install just one outlet. Right now I have all of my computer stuff in my closet running off of extension chords from various outlets around the room to attempt to distribute the power. But when I build a custom pc, it will pull a lot of power. I have to be thinking about that. I will probably pay my grandfather (an electrician) to add quality outlets that are properly grounded to my closet. I will also have to mess with getting a permit for him to do that and then have to have an inspector come and check it out before I use it. Wiring isnt cheap, people steal copper wiring from houses and sell it for scrap. I have rolls of wire in my garage worth a lot of $.
Cost like that can make or break a fish room. Your land lord will probably not agree to it all. That also means that she should have it in the lease agreement and something about a week or 30 days bla bla bla. She probably wont agree to any of it. She may just laugh at you. She may not like the tanks that you have set up right now.
I dont want to be the nagging king, but you really have to look at it from all angles. In order to make that room safe for a fish room, you are looking to spend WAY more than you are on the tanks.
If you and your grandfather get along and he has a basement that you can set up a fish room up in, then go for that. Otherwise, I would pass and just keep the tanks you have while you still can.
