= reverse osmosis
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check this out:
but if that doesn't answer your question, reverse osmosis water is water filtered using a reverse osmosis process. Deionizing the water takes it a step further, removing nearly all the dissolved particle, including phosphates. You can get a filter setup that does this for about $135 shipped on ebay.
It seems like you have a lot in your tank considering it's only a month old.
Take it slow!!!