3a : to place or invest in such a manner as to make unavailable for other purposes their money was tied up in stocksb : to restrain from normal movement, operation, or progress traffic was tied up for miles. 4a : to keep busy was tied up in conference all dayb : to preempt the use of tied up the phone for an hour.
A 20-gallon tank is the minimum tank size for a reef or saltwater tank. Although it may be harder to maintain than a bigger tank, it is possible to create a saltwater tank using 20 gallons. Be mindful of the fish stocking to ensure that too many fish do not over-pollute the system.
However, salt water has a greater weight because of the minerals that are dissolved in it. Each gallon of sea water contains about 4.5 ounces of salt, which is about 3.5 percent of its total weight. A cubic foot of salt water weighs about 64 pounds. Because salt water is heavier, it is able to buoy objects up with a greater force, so objects float slightly better in salt water.