Hi I have a 30 gallon aquarium with 1 bangii cardinal and 2 clowns and every thing is great ammonia is 0 -nitrite 0 -nitrate 20 ppm- ph8.0-temp 78F -sg is 1.022-. Is a sg of 1.022 to low for live rock. I would like to add some snails or a shrimp or two to the aquarium but I think a nitrate of 20 ppm is to high for inverts what do you think and if it is to high how can I lower it? I do a 20% water change every two weeks. Thanks.

