how much vinegar

Wow that's going to take a lot of vinegar at least 100 gallons IMO at a 50/50 ratio. I use it straight for cleaning equipment. Vinegar is already only a 5% acid solution.

Find some muriatic acid at the hardware store and dilute to a 10:1 ratio. It's cheaper and works much faster than vinegar, especially for big jobs...but is still going to cost quite a bit for a 220 gallon tank.

 

Heres some great reading on it http://www.reefcentral.com/forums/s...p=15966089

 

I don't know if you are local, but I have half a jug (1/2 gallon?) of muriatic acid you (or anyone) can have I think somewhere around here.

 

You definitely have caught the fever/DesktopModules/ActiveForums/themes/_default/emoticons/w00t.gif  If you use the muratic acid, just be careful!  If the tank is glass, I'd be watchful of the silicone when using the acid.    Personally, I'd use vinegar...