Can't keep nitrates under 20ppm


Premium Member
My 125g tank has been cycled and set up for about 4 months. I have a total water volume of about 180g including sump and fuge. I purchased aquacultered LR from FL. I have a CUC that consists of crabs, snails, cucumbers and 3 brittle stars. I can not get my nitrates to stay under 20ppm. I do water changes and they come down to between 5-10 and then the next day they are back to 20 again. They have never been over 20...which is good I guess. I want this to eventually be a reef aquarium, but am afraid to add corals or anything because of the nitrates.

About 2 weeks ago I added 1lb of Chaeto to the fuge. There is also LR rubble in there, but no sand.

I have a DAS Ex-2 skimmer. I have a TLF Phosban reactor. The media in there is as old as the tank. I also run carbon in a reactor and change that every 2 weeks. I use a filter sock that stays on for 2-3 days and then off for 2-3 days.

ph - 8.1
salilinity - 1.024
ammonia - 0
nitrites - 0
alkalinity - 9dKh
temp - 78 - 80

Any other suggestions on what to do to bring them down and keep them down??


New member
Dead snails???? Sounds like you have something decaying in tank with that little bioload??? What was the nitrate level after you cycled? What was your water change after cycle?


Premium Member
Right after the tank cycled the nitrates stayed at about 5 - 10ppm. When they first went up to 20ppm I did a water change every day for 2 weeks. It would go back down and then up to 20 again. It has never been below 5ppm. Recently I have been doing weekly water changes...about 25 gallons at a time. i use RO/DI water. I premix the water in Brute cans and it sits for a week with a thermometer, PH, air stone in there. I even checked the nitrates of the new salt water thinking that was the problem and they were 0.

I do not have an exact count on my snails or crabs (they came with the LR and LS) but it does not appear that they are disappearing.


In Memoriam
THe fuge is only another tool used.It may help but removeing the source is only cure.
Whats used for water movement?
Water source?
All stock you have?
Amount of LR and substrate.


New member
what and how much are you feeding? Are you growing the chaeto w/ a light? Or did you just literally throw it in there?


New member
Someone on here recently explained that even though our live rock will reach a place of having enough good bacteria to handle our bioloads from fish, the rock itself still has things in it that are dying and decaying. If that be the case, then we are naturally going to have a few more moments where things don't stay stable. I guess it's just why they say it takes so long for a tank to mature.

My tank has been up since January and I just finally saw my nitrates hit 20 for the first time and up til now it never has. But the nitrites and ammonia are zero. So I'm just going to turn up the water changes and be happy.



Premium Member
Water movement = Vortech and Korilla 3
Water source = Ro/DI water. TDS = 0.
125lbs of sand, 250 lbs of LR

Chaeto does have a light. I can not remember the exact light, but I am using the same one that Melev suggested on his website. I run the lighting for 12 hours a day, opposite the DT light. The fuge is being gravity fed from the overflow with a BV to control flow. I didn't think there was enough movement in there so I had an extra Korilla 2 that I stuck in there just a few days ago.

Stock = CUC (blue legged hermit crabs, snails, 3 brittle stars, 4 cucumbers) Also, 1 Blenny, 1 - 3" Hippo Tang, 1 - 3" Powder Brown Tang. Everyone seems happy, healthy, and eating well.

I was feeding twice a day. I would rotate between Rod's Food or Brine and Mysis Shrimp soaked in Garlic Extreme and Selcon. I have recently cut the feedings back to once a day thinking that maybe I was over feeding.


New member
A deep sand bed will help, but it takes about 6 months before it is in full action. The chaeto should help, just give it time. Increase the lighting to 16 hours for the chaeto. You may need to add chelated iron to help the chaeto if it doesn't grow.

Do 10% water changes weekly. Don't over feed. Run your skimmer wet for a while. You could set up a remote DSB (in fuge is good), but this will take time to work like I said.