mike3epanda said:
... I guess i have to get one now, but is 2 stage filter good enough?
Well... I suppose it's better than using nothing at all and using straight tap water. But with how much money you're eventually going to end up with in this tank, is "good enough" really what you want to start out with?
I understand you're on a budget - I've followed your other posts. You can have a saltwater tank really cheap - no problem. Skip the skimmer, skimp on live rock, use tap water with cheap salt, only change water every couple months, and don't buy test kits but instead rely on how agitated your fish look. Plenty of folks do it. But you end up with something that becomes so frustratingly time-consuming as you battle one problem to the next, that you'll most likely give it up in under a year as being "too much hassle" and assume that saltwater tanks truly are impossible like they're often made out to be.
Hopefully I'm not coming off as preachy or condescending, but you really need to ask yourself why you want this tank. While there are a lot of ways to save money in setting up a tank (DIY skimmers, second-hand equipment, etc...) doing it "on the cheap" will not save you money in the long run.
The good folks before my post speak the truth - water is the main ingredient! Even in my area (Western Washington), where we have absolutely awesome water, I wouldn't think about putting it straight from the tap into my tank. I started out with minimal filtration (a Kold Steril unit, not RO... but don't go that route if you're looking for cheap!) and tested the filtered water. At the time, there were no nitrates in it. But about 3 months after the tank was going, nitrates started showing up in my source water. I ended up adding a DI unit inline with the Kold Steril to get me back to 0 nitrates. Point is... I should've started that way because it was silly of me to think my water chemistry would always stay the same. I now don't have to worry about what my water company is doing behind my back because my water is consistant batch to batch - because it's pure. Consistancy is one of the keys to this hobby, and consistant water leaves you one less thing to worry about.
PS... the filter media in the Kold Steril units are pretty much the same thing as poly-filters which change color as they suck up the contaminants. The color depends on what it's taking out of the water. Mine are turning a nice shade of blue, which means it's taking copper out of my water. Copper is a big no-no if you're considering any corals. There's more in water than just nitrates, ammonia, and phospates... just an FYI.