whats you SG in the 125 at right now? and whats it at in the 90? I would not empty the 90 untill you have the salt on hand to match the water up. If you try to use the water from the 90 to add to the 125 with a lower SG it will only lower it fruther as you'll be thinning the salt content out . be patient and wait till the morning and get some more salt. you'll save some headaches.