Originally Posted by ophiura
Wow, as mentioned, that is very low. If you want to keep inverts, you need it at a minimum of 1.024, ideally 1.025-1.026.
However if you just want to keep fish (literally, just fish - no snails, shrimp, etc) then 1.019 would be OK.
If there is nothing in the tank it can be raised relatively quickly.
This is what I was saying. Since you have nothing in the tank there is no need to slowly raise the SG (although when you have fish/inverts/coral in the tnak an increase of around .002 a day is enough), IMO I would mix up a batch of saltwater with a very high SG and do a water change. I would still go the route of mixing up the water for 24 hours prior to adding to your tank. Since you have a 40 gallon tank i would do about a 10 gallon change with SG of around 1.030 - this should get your tank a little closer to your target of 1.025.
If you have things on your LR that yo uwant to keep (good hitch hikers), then you do need to raise the SG slowly b/c they will die otherwise (if they haven't died already from the low SG).