I installed a new tank in my 71, and within 1 year it was getting this white haze on it and it looked BAD. The Galvanizing on the new tanks won't always stop problems. I replaced the tank and cleared it with the satin clear from Eastwood as Albert said, and never had a problem again. I also cleared the new tank in my 68 and it still looks like the day I installed it, 2 years later.
For the $5.00 a can of satin clear costs, it's a no brainer. It will save the $200 tank, and keep it looking new. Here's a shot of the tank in my 71, with the hazing after less than 1 year, and this was on a car kept in a climate controlled garage, and trailered to shows.
I was told by the Quanta, where I bought the tank, that it is not guaranteed against this hazing. I learned this lesson the hard way. Clear it!! The satin clear will not change the appearance of the galvanizing and it will keep the hazing from starting.