Joe, I responded to your PM. With a nano, I'd use distilled. It's cheap. I do 2 gallons a week and about a gallon in auto top off. Thats about $2.50 a week in water. I get mine from Target. Algae will be a problem in a nano if you use tap, no matter how much you treat it and with that small water volume you will ned all the stability help you can get so don't handicap yourself right off the bat by using anything less than ideal water.
Also, while the store may have told you dump everything in and go cause it cured and "live", you need to remember you are dealing with a nano, not 100 gallons of tank volume. Your patience needs to be rediculous!!!! The hardest thing you will have to do is learn to walk away and let the tank be. Even the process of moving rock from the bag to the tank is enough to kill something and cause a small cycle. When I first started my 12G was VERY sensetive and took 2 months to cycle (started with dry sand and a LR rubble). Over a year now and I still add very slow.
Algae will be most responsive to minute changes. If the lighting spectrum even changes a hair in mine (MH lights) it is visible in the tank. Which means I change the lights, then wait a week or 2 to let the tank settle down again until I see signs of stability.
Temps swings will be an issue for you depending on where your tank is located in the house and the lighting you use. I have to run a chiller and a heater to keep the tank stable at 78-79. Of course your tank's tolerance for temp will be determined by what you plan to keep in it. I keep mostly SPS, so I need a relatively consistant temp with the lights I have. If I just had fish and some inverts, then I wouldn't care if my tank swung 5 degrees a day or so. Everyone's milage and opinions on this vary.
Like I said in the PM too, an auto top off will be your best friend in a nano. No need to spend $$$$ on an Tunze osmolator. They are nice, but I set mine up for less than $20 with a float switch and a little powerhead.
