I'm craig and I have just set up my 1st marine aquarium after having kept freshwater fish for several years.
If my hydrometer reading is slightly lower than I want what is the safest way to increase the salt level? .
The main thing you want to keep in mind is don't do anything drastic w/the saltwater in your tank. You don't want to drastically lower or raise your specific gravity if you have fish, live rock, live sand or inverts in the tank. With that in mind I think the best way to get to your desired reading is through water changes and adding water with a slightly higher SG.
If you don't have anything in the tank yet and you're just setting up, just add a little more mix and let it circulate for a day or two to stabilize before testing SG again.
I agree with Mike. If you make any changes do it slow and easy. I have successfully adjusted the specific gravity in my salt water tank while the fish where in it. I placed a small amount of salt mix in a cup and added tank water, trying to dissolve as much of the salt into the cup of water as possible. I then slowly added the salt water into the tank. I waited about an hour and tested the water. I repeated the process until the specific gravity was spot on.
Saltwater tanks are great to look at but loads of work and you have to stay on top of things. Regular water changes are a must and if you haven't done so already, I would buy some extra buckets, heaters, a small air pump (with air stones) and small power head or two. Remember, once the fish are in the tank, the water you are putting in, after a change, must be as close as possible to the water in the tank with regards to PH, specific gravity and temp. Mixing up water in advance of a water change gives you enough time to PH the water and get the specific gravity right. At the same time the heaters will help warm up the water to the same temp as in the tank (less shock to the fish) and the air pump and power head will help to dissolve the salt mix in the bucket.