How much Nitrate is too high?

[stephencraig]

I'm continuing to have Nitrate problems with my corner tank. I did WQ test tonight, and Nitrates were either 80 or 100ppm.

Here are the other tests:
Ammonia 0
Nitrite 0
Kh 12
Ph (after I put buffer in) 8.24

Weird things: I'm never seeing any spike in Nitrites, and not in Ammonia since I had something die in the tank a while back (a couple of months ago).

Other weird things:
My wave tank (the other tank) is:
Ammonia 0
Nitrites 0
Nitrates 0
Kh 15
Ph 8.24

Both tanks are 90/92 gals. Both have a relatively equal # of fish. I feed both tanks exactly the same amounts of food, both in terms of fish food and coral food (coral food consists of DT's, LiquidLife Zoo plankton, and oyster eggs). The corner tank (w/ the high Nitrates) has about 35 - 40 pieces of coral. The wave tank has around 20 - 25 pieces. The corner tank has a sump and Tunze skimmer. The wave tank does not (no sump, Prizm skimmer). The only other major differences I can think of is I have clams, Zoo's, and Xenia in the wave tank (0 Nitrate), whereas I have mainly more "higher end" corals in the corner tank (80 - 100 ppm Nitrate). I did about 20 - 30% water change on the corner tank about a week and a half ago.

Any ideas to 1) what is causing the high Nitrates? 2) when I should really really start worrying (like maybe now?) about the Nitrate level, and 3) ideas to reduce the Nitrates would be greatly appreciated.

Stephen

[fishcrazy]

I was concerned when my spiked up to 30ppm.

[Richard]

Do you have a sandbed in the tank? What type of sand/gravel & how deep?

How much liverock? Is it all liverock or did you use base rock also?

Do you have any type of nutrient sink such as detritus built up in your sump or tank. Do you use mechanical filtration? How often do you clean it?

Bioballs? If so do they look clean or dirty?

Do you have any algae problems like hair algae, slime algae, etc.?

I'm never seeing any spike in Nitrites, and not in Ammonia since I had something die in the tank a while back

That's really not unusual. It just means you have a healthy population of aerobic nitrifying bacteria. The reason your nitrates are high is that you do not have enough anaerobic denitrifying bacteria or that you have some type of nutrient sink or both.

How much is too much depends on what corals your keeping but it's always best to shoot for at least less than 10 for a reef tank.

[GaryP]

Just wanted to back up what Richard said. There are basically 2 approached to nitrate control:

1. Deep sand bed - at least 4 inches of sugar fine sand that create a low oxygen area for denitrifying bacteria to live. They require such an environment. They are not the same type of bacteria that process ammonia and nitrite. Those are the kind that you would find in bioballs, the exposed surfaces of live rock, and the first couple of inches of a sand bed.

2. Bare bottom - This is more of a high maintenance, equipment intensive approach. Even folks that are doing this tend to have some nitrate problems. The idea is to maintain really high flow to prevent detritus from collecting, a highly effective skimmer to remove as much as possible, and do a lot of siphoning to remove as much detritus as possible.

Other things you can do include: Run carbon to remove as much dissolved organic matter as possible, make sure your skimmer is working effectively by making sure the pump and eductor do not have any scale buildup and it is tuned correctly, running physical filtration to remove any solid detritus, and adding a refugium. Clams will also help remove nitrates to some degree.

You may also want to talk to Richard about the Hiatt method that seems to be helpful in controlling nitrates. There are a couple threads on this method on here.

High nitrates are simply of more nutrient being imported (from food), then is being exported through things like skimming, filtration, and denitrifying bacteria. Rarely is any one single approach effective. It takes a combination of the type of things mentioned here.

I would also guess that your phosphates are probably fairly high if your nitrates are that high. They usually go hand in hand. High phosphates usually result in problems with nuisance algaes (hair, bubble, cyano, etc.) If detritus buildup is part of the problem, that can also cause issues with cyano.

[Willow]

ok... if high phosphates usually go hand in hand with high nitrogen... would phosphates also spike during cycling?

And how do you go about lowering high phosphates? Or do they drop on their own after awhile?

thanks (& not meaning to hijack..)

[GaryP]

Yes, phosphates are usually high during cycling. That's why we often see algae blooms. The same things I mentioned in regards to decreasing nitrates will work for phosphates. There is one additional one though. Phosphate absorbers.

[Willow]

Well.. is it a good idea to try and lower the levels in a cycling tank?.. Or is it better in the long run to let them come down on their own?


btw thanks for the info.. I haven't seen these particular questions answered anywhere else before.. and it's good to know for future reference...

[GaryP]

IMO, its better to just let it run its course. The reason there is excess nutrients is because the bacterial cultures haven't caught up to the amount of food available. By reducing levels you are cutting back on their food and you may be preventing a mature microfauna to develop.

Of course this requires paitence. That's not something that most new tank owners have in excess. They'd rather throw raw shrimp in there and go buy damsels that they will regret forever.

[Willow]

makes sense to me..

Thanks!