CraigJ,
As fixit said, high nitrates do not usually bother fish to a point. At some point, it will but hopefully you will not let it get to that extreme. I should also add that this is for existing fish. Nitrates usually rise slow over time and your existing fish will adapt to higher levels. If you add a new fish to high nitrate tanks, it will most likely die as it will shock the fish' system by burning their gills.
The skimmer does not lower nitrates, but can help to slow the rate at which nitrates increase by removing excess protein before it can break down into nitrates.
Do the water change. That is the only way to reduce the nitrates fast. Sometime the nitrates will increase faster than water changes can control them. This happened to me a while back and my nitrates reached around 90. I did a 75% water change and vacuumed the CC and got it down to 10. If you have CC, you need to vacuum it regularly as this is a nitrate trap. With CC, I try not to let it get over 40 between water changes as it is hard to keep it much lower.
Caulerpa sounds interesting and I'm interested in hearing how to use it also. Do you grow it in a refugium or is it in the main tank?
Tangman
