if you keep adding 1.001 it does not stack it will make your water 1.001, you need to get your tank to 1.005 and the recipe above will give you 1.005
what is your salinity at right now
if it is at 1.003 pull out 5g of your water then replace it with 5g mixed this way.
2cup of marine salt in a 5g pail, add 1/3 bucket of hot water to dissolve the salt then 2/3 of the water to bring the temp in the bucket to match the temp in the tank, add 1/2 cap of prime to the 5g bucket to take out bad stuff and help condition tank water. then add new mix to the tank about 3 cups every 10 minutes or so.
That should bring up your salinity a bit in the tank then take a measurement to see where it is at