Welcome aboard!
Okay, a couple points:
Don't go down and use sand from your local beach. It's polluted. Now you may think it's clean, but it's polluted. Try this, take a dinner plate and put a bit of water in it, then put some dirt from your yard in the H2O. Stir it up. Notice how some of the dirt settles on the bottom, but a lot of it goes to and sticks on the outer edges? You just created a mini ocean, and your stirring of the H2O was bascially the action of the waves.
See, every drop of oil or gas from a boat, each ml of medical waste, every bit of human waste that is in the ocean, some of it gets to the shore through the natural action of the waves. When you confine that small bit of pollution to a small confined area, it concentrates the effects of the pollution: pretty rough on your tank.
Now since the ocean's so big, it can process and handle much of the pollution (Greenpeace members leave me alone, I'm speaking only for the sake of this post). But in a small confined tank that can't spread the pollution over thousands of square miles of H20 & Bio filter, the contaminants become even more deadly.
Do a search for "LS" or "sand" or "Live Sand" on this site and you will come up with a myriad of solutions.
Two: If you have the cash for a 150, hopefully you have the ching for an RO unit. I sprung $125 for a Kent 17 gallon per day and wouldn't be without it. They are worth it. If you calculate what your time is worth and transfer that to how much time you spend going to the pet store or grocery store to get RO H2O, the RO units are comparatively cheap.
