Get a new sand because you'll regreat trying to go cheap . Once you wash it it will look fine and you will say to yourself oh they don't know what's up. But then you see yourself end up posting on here again saying why are my nitrates never go down, why do I have high phosphates, why can't I battle the diatoms on my sand . Shallow Sandbeds are usually replaced every 2 years unless they're deep then those are thrown out in parts over longer period, basically they are sewer collectors. Not to say people don't do it. But if you are short on money I would suggest to get the live rock first start cycling your tank, and pick up a bag of dry aragonite from the store when you can.
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