Congrats on the wonderful project you have ahead of you. Think it through, do it right, and it will vastly increase your enjoyment of the hobby. Doing the proper planning and construction now, while not a small job, will pay huge dividends in easier maintenance throughout the coming years.
Excellent move on the laundry/slop sink idea. Worth its weight in gold, both for aquarium purposes and for general use.
Give careful consideration to the ventilation and humidity control in the basement. Keeping all tanks covered will help immensely but you still need to make sure you have sufficient dehumidifier capacity and ventilation to maintain acceptable low humidity levels.
Sounds like you are planning on three large-ish tanks and nothing else? I'd suggest building a rack and installing at least a couple or three smaller tanks for use as hospital and/or quarantine tanks. You will eventually need them, and it's nice not to need to mess around with temporary plastic bins or other makeshift containers.
You can definitely start off with "regular" tanks and modify them later with bulkheads, overflows, sumps, etc...but it's far easier to set them up that way from the get-go. If you haven't drilled a glass tank before, the first time you do it will be a nerve-wracking experience but it is surprisingly simple if you go slow and be careful. And I would never consider starting a project like yours without designing it to utilize sumps for filtration rather than HOB's or, worst of all, canisters.
Likewise, putting the plumbing in place to handle water changes is essential. I change a lot of water and do it entirely by opening and closing the appropriate valves; no buckets, siphons, sucking on hoses or other nonsense. You can do it using a lovely network of PVC pipes, creating an impressive and techie-looking work of art...or you can do it faster, easier, uglier and cheaper using garden hoses installed in a semi-permanent arrangement which is easily modified and/or added-onto in future.
Every basement fishroom I've had has required the waste water to be pumped up to the outdoors. If you are on a municipal sanitary sewer system, it's much easier because the waste water can be sent into that drainage system; if you're on a private septic bed as I have always been, you must not send your waste water down that drain because your septic bed has a finite life and you will shorten it drastically by sending hundreds of extra gallons of water into it on a weekly basis. And being a Canuck, you know that once the waste water leaves your basement you will need to be concerned about where it goes during the winter to avoid creating a skating rink next to your house. I pump my waste water in the summertime to an outside Big O pipe buried under the lawn that carries the water into a pasture adjacent to my lawn, or if I flick the valve the water flows to an outdoor faucet that allows me to water gardens, flowers, etc. with nice poop-enriched fish water. During the winter the winter is also pumped to that outside faucet; I need to lay a hose from that faucet into the field to get the water away from the house, and must pick up the hose immediately afterwards to prevent freezing. It's the biggest flaw in my waste water management system, but otherwise I'd need to rely on a heated drain line leading from the house and I don't want to do that; YMMV.
The problems associated with waste water disposal during the winter months is the main reason I haven't gone to a continuous-drip water change system; if such a thing works in your situation that would be the way to go. I can't comment as I have little experience with that idea; hopefully
wednesday13
or someone else in the know can chime in with info on it.
Your new change water can come from a storage tank that you keep filled up, if there's room for that. Mine sit in the crawlspace adjacent to the basement, allowing water to flow by gravity from them into the aquaria. This also lets you heat, aerate, dechlorinate or otherwise pretreat the water in the storage tank before use. Alternatively, you can install an on-demand water heater for your fishroom, precluding the need for storage but giving you essentially limitless amounts of warm water without worrying about overtaxing your standard water heater tank during large water changes. I have both set-ups in place but rarely use the on-demand system, since my storage tanks have sufficient capacity to change all my water at once.
Dang! Long post already, and I've just scratched the surface. There's lots to think about, lots to plan, plenty of choices to mull over. Think three times...measure twice...cut once.
Good luck! Do the work right at the beginning, then just reap the rewards of careful planning and design in the years to come.
