Your levels are not that bad considering your tank is so new.
I assume that you mean that your specific gravity is 1.025 as 1.25 would have killed everything by now.
Once sure way to drop your alk and raise your calcium is to add calcium chloride starting in very small amounts that gradually increase. Water can only contain so many dissolved solids before it becomes saturated. So adding only calcium chloride will help to balance your tank in two ways - 1. By forcing some of the alk to precipitate out and 2. both calcium and alk will be consumed by your tank's critters and by only replacing the calcium the alk should naturally subside on its own. The one word of caution with this method is that adding too much at one time could lead to a "snowstorm" of precipitation so start slow and test often. Try to target your calcium around 380-400 for now. Try raising your calcium by 10 ppm every day.