First post on this forum and so far I've met a few nice people so I kinda like it here lol Had a warm welcome but now down to business!

I'm building an extremely small (as ponds go) indoor pond that is about 115 gallons. The water level is 21 inches from the top of the bottom board if that makes sense. Both sides are 36 inches long so it holds about 115 gallons. 

I've done a lot of research (one of my hobbies is researching things so that is helpful in this hobby) but I've read a lot of different rules when stocking coldwater tanks. Goldfish especially.

Originally I wanted to get 3 single tailed goldfish of the same type (Shubunkin for example) and I've read a lot of mixed stocking suggestions. They range from blatantly cruel 1-10 gallons per fish to 75 gallons per fish. I've seen a lot of the 20 for the first and 10 for every other but that is mostly for fancies.

So my first plan:
3 Shubunkins
or
3 Comets 
or
3 Commons

Second plan:
1 Fantail 
1 Ryukin
1 Oranda

With my research habits, I know the fancies will be okay but the single tails are questionable.. I am leaning towards the fancies atm because more space for smaller fish is always better.

Would the single tails be okay? And how would you guys stock this tank (bare bottom atm)? I am open minded and I would enjoy any suggestions given.

Also, I've heard that they like sunlight and it helps with their color development. Because of this I'm wondering if I should place the tank near a window? I know this will cause algae growth, but I am also building an algae scrubber and growing duckweed and hornwort so i think it will be okay. In short, will this mess up my temperature or have negative effects?

Thanks! - Raymond