There's a gravel calculator right on the bag. Do the math.
Each 50-pound bag of QUIKRETE® All-Purpose Gravel contains approximately 0.5 cubic feet of gravel. To cover an area of 37 feet by 25 feet at 2 inches deep, you will need 154.2 cubic feet, or 309 50-pound bags. Yields will vary with waste, uneven subgrade, etc.
There are actually calculators online you can search for, but to really answer you would need to know how deep you need the gravel as well.
1 bag is .5 cu feet. You need approx 93 cu feet which would be 187 bags.
QUIKRETE® All-Purpose Gravel is nominally 3/8 minus aggregate, so it is smaller than the ¾” gravel. Both products are suitable for use as a drainage base for a concrete slab.
I would never use this product in my fish tank. I would use it to create an outdoor pond, or swimming pool.
QUIKRETE® All Purpose Gravel is high quality clean gravel with an approximate top size of 3/8" (10 mm), suitable for landscaping, concrete manufacture and a variety of other purposes. It can be driven upon.
QUIKRETE All Purpose Gravel is suitable for all construction products requiring a quality -3/8" aggregate.
Each 50-pound bag of QUIKRETE® All-Purpose Gravel contains approximately 0.5 cubic feet of sand. For an area of 11 feet by 10 feet at 2” deep, you will need 18-1/3 cubic feet of gravel, or 37 50-pound bags. Yields will vary with waste, uneven subgrade, etc.
Well as posted right on the web-site ( Quikrete 50 lb. All-Purpose Gravel Model# 115150 (141) $510 )