Nitrates

[stacyadless]

If I want to get the nitrate levels down in my 70 gal tank how frequently should I be doing water changes, and what percentages. Our levels fluctuate from 40 all the way to 160! We inherited this tank when we bought the house, so the tank is several years old. Yes, I think I have been overfeeding, and I have cut down. The tank has two clowns, two damsels, and one gobie. Right now we are doing 10 percent water changes with water from our LFS. What do we need to be doing in frequency/percents of water changes? Right now our nitrites and ammonia are 0. Ph is 8.2. Our old filter died, and we discovered it was not big enough for our tank (Eheim Ecco) we replaced it with a Fluval cannister for 100 gal tanks about two weeks ago. Also, we just discovered vaccuming and have been doing that on the last two water changes.
Thanks for any advice!

 

[nycbob]

what kind of substrate does it hv? how much live rocks? try to change at least 10% weekly. having macroalgae like cheato will help big time.

 

[stacyadless]

We don't have live rock. Our LFS said we just have base rock. We have some coral, but we are just now figuring out what we have. Our substrate is sand. I think I have quiet a lot of copepods, we added about an inch of sand (not live) yesterday, per instructions from our LFS. Our old sand was a very thin layer with a lot of bare spots especially after my husband started to vcuum. What is cheto? Is more than 10 percent too aggressive? Can lowering the trates too fast actually hurt our poor fish that have been living in this tank for a long time?