Constantly spiked Nitrate?

[JonPM]

My tank's nitrate level is constantly spiked. After i do a water change it drops, but it only takes a couple days for it to get high again. My tanks been cycling for about 3 months now. I have some live rock, a cleaner crew, and a blue tang. I'm running a protein skimmer as well as an internal water pump. Anyone have any ideas as to whats causing? My other levels are sitting around zero. Ph is 8.2.

Thanks for any help.

 

[DEmigh]

Check your replacement water for nitrate.

Also, are you using any pH buffers? Many of those include nitrates.

When you do water changes, do you take the opportunity to vacumn detritus from your substrate (presuming you don't have a DSB)

How much/how often are you feeding?

If nobody else has said it yet,

Welcome to Aquaria Central

 

[JonPM]

Thanks. Yeah I use Proper pH 8.2 by Aquarium Pharmaceuticals.
I'll usually vacuum the bottom and try to remove as much of the debris as possible.
I feed my blue tang 1/4 of a small ice cube of bloodworms maybe once a day or once every other day.

 

[mogurnda]

How much live rock have you got, and how big is the tank? Nitrate is the natural end product of protein metabolism, and is quite stable in an aerobic environment. It can only leave the tank in a few ways.

1. It can be removed by water changes, as you are doing now. That will only go so far, as the livestock are perfectly happy to make more.

2. It can be consumed by macroalgae, such as caulerpa or chaetomorpha. You then export the nitrogen when you prune them.

3. It can be converted to N2 gas by bacteria living in the hypoxic interior of the live rock, and then bubble out of the tank. You have some live rock, but maybe not enough. Or maybe the rock has not matured to the point that it's getting the job done.

How much NO3 have you got?

 

[JonPM]

I have a small tank. 15 gallon upright with about 5-10lbs live rock.
I didn't really understand #2.
How do I know if my live rock is matured yet? THey have already started growing different things on their surfaces. One is turning a dark green, another has some light green and purple.
How do I test my NO3? If that's nitrites, then its at zero.

 

[OrionGirl]

NO3 is nitrate.

A blue tang in a 15 gallon tang is likely part of the problem--they really need much larger tanks to thrive, and in a small tank, are a huge bioload. Blues can get up to 9-10 inches easily, at which point it won't be able to turn around in the current tank. It's producing a lot more waste than that size tank--even packed full of LR--will be able to handle.

I would take the fish back, and find something more appropriate for a small tank. Sorry. I'm currently debating even adding a fish to my 10 gallon tank--inverts are typically easier to maintain in a small tank than even small fish.

 

[yonderway]

An alternative approach to managing nitrate would be to establish a refugium sharing water with your main tank.

 

[OrionGirl]

While adding a fuge might be a temporary solution, and certainly beneficial to nitrate reduction, it will not address the problem of a tang being in a 15 gallon tank.

 

[TKOS]

Typical tanks that use live rock aim for 1 to 1.5 lbs per gallon. So you really need 15-25 lbs of live rock. But I agree that any tang in a 15 gallon tank is a bad idea. Perhaps a clown would be a better choice, or some type of goby.

Also, are you using some sort of filter as well. I was unsure from your post if you were.

 

[johnnyxxl]

I was wondering are there many fish for a saltwater tank that size really other than a goby? I think most all the informaiton on saltwater fish are wanting a larger tank say 30 or larger?