Nitrates not lowering

[orcafood]

Hi,
In my new ninety gallon setup I took everything from the previous owner, including water, sand, and fish. It has an ASM G4 and two 175 metal halides complemented by two actinic VHOs. The nitrates are around 60 PPM. The man at my lfs said to do a few water changes every week to restore the tank. I did one yesterday and today the nitrates are around 120 PPM. I vaccumed the sand and everything. What should I do?

Red slime algae is taking over a few of the rocks.
I also have a few coral skeletons that came with the tank. Should I take those out?

[MalHavoc]

Nitrates won't climb unless there's a source of them. What's in the tank for livestock? How much/what are you feeding? Are you doing water changes with purified RO/DI water, or are you using tap water? What kind of salt? Have you tested your water change water for nitrates? did anything die in the tank?

[Sk8r]

Ok, basically this is a new setup---I'd have used just the rock, dumped the sand, but you're into this in this mode, so we go with it. We need every test parameter you've got, size, equipment, sump/y/n. We're operating in the dark otherwise.

But in general I'd assume your tank is trying to cycle and the water changes and sand cleaning are interfering with this process. In the cycling process, the nitrate and ammonia spike high, lethally high, to most everything but bacteria, at the worst; sometimes less than that. You let it run un-interfered-with until the ammonia goes away and the nitrate falls. How can it? The bacteria in the sandbed layer themselves like a torte cake and start processing like a factory: the rocks have similar bacteria that need to sort themselves out as to where up/down under-sand/above in the light are in this incarnation of the tank. Your fish and inverts, if any, should be in a quarantine tank while this bacterial sortout is going on, a small bare tank with just a carbon/floss filter and tested daily for salinity, temp, alkalinity, nitrate/ammonia, ph: you can water-change THAT but not the cycling display tank. I think your lfs is trying to set you up without a cycle happening, and I don't think it's working: sounds as if it's started, and it just needs to run itself to completion, set up the layering in the sandbed [after which it should not be cleaned] and in general just put itself into biochemical operation.

HTH.

[amazd]

Two points: DONT VACUUM the substrate. You're removing lots of helpful bacteria that will eventually get things in balance. Rather than clean the substrate yourself, purchase some sand gobies and nassarius snails to do it for you. Secondly, as MalHavoc said, test your change water. It could be you're introducing the ammonia source for nitrates from your change water. If you have an RO system check the filter cartridges. If they're dark orange, that's a huge problem. Brand new ones are white.

[orcafood]

Ok thanks alot.
Heres the stats:
temp - 79 F
salinity - 1.023 SG (tested with instant ocean swing needle hydrometer)
ammonia - ? will get test kit tonight
nitrite - 0 ppm
nitrate - 120 ppm
PH - 8.2
KH - 240 ppm
calcium - 450 ppm

fish and invert stocking:
2.5 in regal tang
4 in fox face lo
3 in mandarin dragonette
2 in fire goby
1.5 in royal gramma

1.5 in emerald crab
2.5 in coral banded shrimp
3X snails (dunno what type)
5-6 in brittle starfish

feeding:
2-3 times a week with thawed and washed frozen plankton and mysis shrimp
2-3 times a week romaine lettuce

setup:
CPR CS102 Overflow Box
15 gallon rubbermaid sump
ASM G4 Skimmer sitting in sump
hydor theo 400 watt heater
Mag drive 12 return pump
3 maxi power heads (dunno how strong)
5-6 in DSB
90 lb "live rock" (how do I even know its alive?)

lighting:
2X 175 watt Ushio metal halides
2X 96 watt blue actinic VHOs
2X 20 watt fluorescent bulbs
2X 4 in computer fans

fluorescents turn on at 6 AM
actinic lights turn on at Noon
computer fans turn on at 2 PM
metal halides turn on at 2 PM
metal halides turn off at 7 PM
computer fans turn off at 7 PM
actinic lights turn off at 8 PM
fluorescents turn off at 10 PM

I have been using distilled water in an auto top off system (10 gallon) and I have been mixing the distilled water with salt for water changes. Its just you regular old Kroger's distilled water


Ill take some pictures if that would help?