Help...How can I convince them?

[Desertponder]

bluekrissyspike took the words right out of my mouth.
All the time I'm reading through this thread I'm thinking, this kid needs to get a stock tank.
If you're parents are set on not wanting a pond in the yard then you need to get creative and find a happy medium that they can live with and works for your fish.
You could probably find a good used stock tank and not have to put out a great deal of money. I put a classified ad in a local paper last summer looking for large stock tanks reasonably priced and I ended up with 3 - 800 gallons tanks for FREE! I'm using two of them right now for my lilies.
You can make your own filter setups very easily and inexpensive.
Its a different approach to work on your parents. You may not like your parents attitude towards this but it is their house and their decision. When you have your own place some day you can have the pond you want.
For now, ask them for a stock tank set up and show that you can take care of it.

 

[Kashta]

Sounds like an excellent suggestion. I'd definitely look into that myself if I had a yard to set up a pond of my own.

 

[PallasAthena]

Sounds like an excellent suggestion. I'd definitely look into that myself if I had a yard to set up a pond of my own.

Sounds like an excellent suggestion to me, too. And if your parents don't think that a stock tank would look pretty in the yard, you can just show them this thread! Jennie Beth's pond is gorgeous, and it sounds like it would be much easier for you than worrying about liners and things. You could even bury the thing in your pre-dug hole to help keep the temp down enough for your goldfish.