Help with new tank

[ronsunni]

I am having some problems. The tank is 135 gal. long hex with an overflow which is full of bio balls. Under the tank there is a 30 gal. three chamber sump. I have bio balls in the first chamber and this is were the overflow goes into, a protein skimmer in the second chamber and the two return pumps (Rio 2100) in the last chamber.
I put 135lbs. of Fiji aquaculture live rock in the tank 4 weeks ago. The ammonia levels went to 0.8 + and fell to 0.0 within a week. The nitrites have been at 6.0 since the ammonia level went to 0.0 . The nitrate level were at 40 . I use RO/DI water.
I did a 25% water change and the nitrites are now 4.0 and the nitrates are 10.
These are the problems
1.The bottom 2 inches of the Aragonite DSB is very dark in color(black)
2.Nitrites at 4.0
3.Nitrates at 10
4.Ammonia 0.0
5.PH 8.4
6.Brown algae on top of highest live rock and sand bed in front of tank
What should be done to fix these problems??
Thanks for the help
Ron

 

[goldrush]

What have you done to encourage the cycle? Is the LR the only thing you put in the tank? Was the LR cured? Was the sand live?

 

[col]

Tank is probably still cycling. By changing water you may have prolonged the cycle.
Just sit it out until nitrites are zero.

 

[birdy]

Agree with col, you are in the middle of your cycle, it sometimes takes a while with a large tank and a large amount of LR, sounds like you had a lot of die off from the rock. Just wait it out, don't do anymore water changes the levels will come down.
As far as the brown algae, they are most likely diatoms, a very normal part of the cycle. Most of them will go away on their own.
Just be patient sounds like a great tank.