why are nitrates bad??

[annabelseymour]

Hi

I have 180 gallon tank with large sump.
Salinity 1.025
Ph 8.1
Ammonia 0
Nitrite 0
Nitrate 30-40

I am doing 20% water changes once a fortnight.

Fish: 2 clowns, 2 firefish, 6 chromis, watchman goby, blue cheek goby, flymo blenny, foxface rabbitfish, 2 firefish, 3 cardinals, cleaner wrasse - nothing added in last 7 weeks.
Inverts: Tuxedo urchin, finger starfish, 2 cleaner shrimps, maxima clam, 10 hermit crabs, lots of snails.
Corals: Mushrooms, zoas, Kenya tree, pulsing xenia, Duncan, plate, elegance, torch, grape, sun, favia, trachyphyllia, lobophyllia.

I know my nitrates are too high, but everything is growing and thriving in my tank. All the corals including lps are growing and spreading.

I assume my nitrates are probably high because the tank is quite highly stocked and I'm probably overfeeding (3 times a day - I alternate frozen, flake, live food and algae), but if everything is happy should I worry???

The only other thing is maybe my skimmer isn't man enough for the job - it's a TMC V2 skim 600. It fills the cup once a week which I empty - should I upgrade?

[Spork3245]

That's a lot of water changes... I'd cut down on the feedings unless you had fish that *need* to be fed 3x per day (2x per day should be fine in most cases, if you have grazers also add some algae/nori to seaweed clip), also, yea, upgrading your skimmer could help.
Nitrates can cause algae growth and high nitrates are bad for most inverts.

[Sk8r]

It's a form of nitrogen that, in excess, is not real friendly to life processes: it's just a nasty byproduct of the tank trying to break down fish poo, and not quite getting through with the process. To vastly oversimplify...it's kind of like the tank toilet overflowing.