If this is a real venture, save your money and make your bones on a Brewmagic or something before going that big.
You can’t be asking questions like, “How long do I Ferment an IPA?” and also be seriously considering that level of outlay for equipment.
That’s just my constructive criticism. With the sheer volume of breweries and product out there, your craft should be sharp as a samurai sword before committing to 1,200 gallons worth of fermenter space.
Methinks perhaps the OP was just funnin’ us, pulling our collective leg if you will. If so, thanks for the morning chuckle, if not, sorry if I’m being an ass.
It is possible ya know that the OP is simply fortunate enough to be able to afford to create the ultimate dream home brewery, and likes to the truly epic house parties.
Check gravity readings when stable it should be done, If you pitched enough yeast.
Dry hop in FV, transfer to brite (when it tastes how you want it to taste) to carbonate, when carbonated to desired carbonation, package or transfer to serving tank. Freshness is key to IPA’s
As for your water search this site for “Bru’n Water” there is plenty of information in which to find your answer.
I’m going to skip your water question because I have no idea since I don’t know what your water is.
For your IPA: If your fermenatation practices are sound 1-2 weeks. Dump or harvest yeast then dry hop. You will want to dry hop via a closed/purged transfer or you will be oxidizing the beer. Or dry hop near the end of fermentation so the yeast scavenge the o2. this is going to be up to you and your technique.
Dry hopping should only take 3-4 days, especially if you are blowing hops into suspension with co2. Or using pump to recirc hops (can be ready in hours that way).
Cold crash in fermentor and remove as much yeast as you can. You want the beer to be ready to package when it is in BT (obviously after carbbed). That’s why it is called BT. The beer is ready to carb and package/keg. Keeping a beer in a BT to clear is pointless because, if you are running a brewery, your BT needs to be cleared ASAP so you can put another beer in the BT to package. In other words, beer should only go to the BT when it is ready to package/keg.