I started with a 5 gallon, then a 20 gallon, and now a 58 gallon SW tank, amongst my much larger FW tanks, thank god FW is so much easier lol.The progress from each sw, cost a lot to upgrade to, and that wasn't going with the "best" equipment. Just my two cents, in no way a shark keeper, SW expert, or anything, not a rant but here goes. I don't have daddy's money at my disposal, sometimes I wish, but no. How much is your dad/ grandpa willing to invest in this venture. How big of a pond are you allowed to go. You do realize that going from a small pond to a bigger to a bigger, etc as these things grow, will take a fortune to upgrade. Let alone any failures in equipment along the way. Just because you get something that costs a lot, doesn't mean it won't fail and you need an emergency plan set up to keep running. I have read thru a lot of your posts and the questions that you ask are very inquisitive, yet very beginner. (again not bashing,please). IMO, which isn't much, but again my 0.02, the gallon-age of the pond isn't as important as the surface area is. Granted they can be ok in somewhat shallow waters, but a 10 foot long pond ain't sh** compared to what they are in a public aquarium, let alone the wild. They can't be constantly turning around. It's like pacing your bedroom. If you go 10x7x3.5 its 1832 gallons, only if you dig a complete rectangle. I don't see how a shark can happily live in a space that small. They aren't like our little FW "sharks" that "happily" swim to and fro in a tank ( aka Rainbow, ID for a short while, etc). Maybe as a pup, but as it grows, where are you going to put the next (much bigger) pond? Will your dad and grandpa give you all that money to start over for making a new pond and getting equipment that can handle that size that will be needed for that now much larger shark? You can't just section off the pond he's in and expand. It will collapse. Do you realize how much it will cost to feed it, or multiple its, someone can speak up on the actual price, just a thought. I just know my RTC is costly, and if you don't have a REAL job, you can't rely on someone else to keep fronting your costs. It will only last so long.