SETUP: FOWLR (dry rock) Recently, I bought a used 55 gallon tank off the internet. However, later after setting up the tank, I found out it’s actually a 75 gallon tank. I already put live sand (amount intended for a 55) in before I found out and it was two full bags, and it looks like it might not be enough. I filled the tank with tap water which I used conditioner and mixed with Instant Ocean salt in a 5 gallon bucket before pouring in. However, I’ve been reading about RO/DI water and feel like I may have made a big mistake not using it. Also, the faucets close to my tank are weirdly shaped and probably can’t be used. I am also getting low salinity readings in my tank, just underneath the red zone on the hydrometer. But again, I’ve started to read that hydrometers aren’t super accurate so I guess I wasted my money buying that instead of a refractometer. The previous owner also had a Fluval 306 canister filter, which I replaced the media out with new media. But I later found the actual plastic intake nozzles were missing and now my tank is sitting here with just a wavemaker cycling the water. My previous fish-keeping experience is freshwater and that was a long time who. I’ve always dreamt of keeping saltwater fish but didn’t have the spare money until now and I’m feeling VERY overwhelmed starting this up. Any tips that can help me clean this mess up are appreciated!