Extremely High Nitrate

[noone]

Since upgrading my 10 gallon to my 12 gallon cube, my nitrate levels have skyrocketed. They are somewhere between 80 and 160 ppm 8O. Ph, ammonia, and nitrite are all in check. I am assuming the best way to lower the levels would be to do water changes, so I went to the grocery store and bought 12 gallons of RO water. I know it probably is not as good as home RO water, but the budget is not there for a home system at the moment. The system was just inspected on the 29th.

My questions are:
How large of water changes should I do?
Is there anything else I can do to help?

I also added some live rock when I changed over. Now my tank is getting a lot of brown/red algae and the rock (which was lightly colored) is now brown . Is there anything I can do about this?

On a happy note, I have no loss of life to report!

 

[i have crabs]

must be from the rock i would guess
i would do a 50g change wait a good 12h at least then do another ,and another untill its under control mabey put a capfull of prime of you have any since it detoxifys nitrate if you have any life in the tank mabey a little bit of that sechem stress reducer stuff what ever its called

 

[mjvincent]

must be from the rock i would guess
i would do a 50g change wait a good 12h at least then do another ,and another untill its under control mabey put a capfull of prime of you have any since it detoxifys nitrate if you have any life in the tank mabey a little bit of that sechem stress reducer stuff what ever its called

I think he meant 5 gallon 8O.