[jones2270]

My tank has been cycleing for about 6 weeks, ammonia and nitrites are at 0 but nitrates are still high( around 80). Should I let it cycle a little longer or do a 5% or 10% water change to get the nitrates down?

[unclejed]

You should definitely do a 25-30% water change. Shane, being new, I will encourage you to provide more info about your tank when asking for help. This is important on a multitude of levels.
In your case, knowing what you have in the tank will help establish how long it took for the Nitrates to accumulate to 80 ppm. Are there fish and how many? How often and how much are you feeding?
Also, many aquarists don't realize that live rock is displacing water volume. Do you have live rock and how much? Depending on how much rock you have and how much water has been displaced, your total water volume in a 30 gal. tank may be 20 gals. So, 30% of 20 = a 6 gal. change, not 9-10 gals. 9-10 gal. change of (truly) 20 gal. of water volume will be a 50% change and that is pushing the envelope, so to say, and disrupting the bacteria and over all chemistry of the tank and therefore stressing the tank and causing an instability.
I hope this isn't too confusing and if there are questions to follow, feel free.

[jones2270]

Well the tank is only 6 weeks old and no livestock. Its a 30 gallon tank with 10 gallon sump. There is 40 lbs of sand and 70 lbs of live rock (45 lbs in tank, 25 lbs of rubble in wet/dry filter). I had already thought of water displacement , thats why I was thinking only 5% or 10 %. I know I have read people do water changes to bring down nitrates in a established tank, but do I need to do this in a newly cycled tank or just wait longer for nature to take its course?

[unclejed]

O.k. At 6 weeks and no live stock, I now would say you have had some die off of course and I would do a "good" water change of 25-30%. I also would add some live bacteria (cycle or bacter) to boost your base and give the tank a substantial amount of filtering capacity. Add the bacteria right after the water change.
By the way, I am not an advocate of multiple water changes to bring down nitrates for the reasons I gave in the earlier post. There are emergencies that happen that warrant that but in this instance with no immediate danger to live stock one change is appropriate at 6 weeks, then, nature will take it's course.

[jones2270]

Ok, Whats the name of the product to add bacteria?

[michael]

why have you got a wet/dry out of interest, is this tank going to be a full blown reef one day or just fish only shane, if a reef then personally id consider removing it and going for a sump instead, how about some info, hello by the way