Dealing with nitrate...

A

axepilot

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Jan 10, 2005
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As some of you know, I'm cycling a 75 gallon FO tank. I have a wet-dry / protein skimmer filter setup. My ammonia is down to zip, my nitrite is currently off scale high, and now my nitrate is on the rise at 20ppm. The last time I ran a marine tank (MANY moons ago), the nitrate solution was regular water changes. I'm guessing that some live rock will help solve this?

Also,
I'm starting to collect a brown dusting on the coral, tank glass and on the sand. I hope this will not be a continual problem.
 
Live rock will help some, as will a sand bed. Both offer places where the anaerobic bacteria that break down nitrates can survive--but these bacteria are slow to develop, and a sand bed must have enough animals to keep it stirred to be effective. There are a few additional options, though--caulerpa or other macro algaes use nitrates, and can be harvested to get it out of the tank completely. Some types of caulerpa can be very invasive--saw blade being the only one I've had experience with. In a large system with VHO lighting, we pulled out about 5 pounds out every other week to keep it from filling the tank. Running a skimmer to pull out organics before they decay will help as well, along with a good cleaner crew (leftover food gets turned into more snail rather than intor nitrates). Won't eliminate the need for water changes (IMO) but helps keep the tank healthy.
 
Every tank produces nitrates, no matter what kind of filtration is used. The key is to keep the export of nitrates in line with the production--and while wet-dry setups can cause problems, this is primarily when they are not maintained properly--sort of like the reputation UGF have in FW setups. Both are effective biological filtration, but they have to be maintained.
 
I'm not looking for the "magic bullet". I have a two inch sand bed that's half live sand. I figure that it will be good for some nitrate reduction. I will conduct regular water changes as I did before. I guess some things don't change..... :)

Now, about this brown algae..........................I'll let the tank cycle before I sound the alarm, but it's got to go!
 
the nitrate cycle

You may know this cycle or you may not anyways i will tell you the hole process

- Fish produce wastes and urine like any animal these wastes usaly build up as AMMONIA.. plant matter can add to this aswell ..
- Ammonia is broken down by the first form of bacteria leaving us with NITRITE..
- Nitrite is broken down by a second form of bacteria that produces NITRATE..

These two forms of bacteria (heterotrophic) form in all tanks quite easily..
This is were most people leave the proces by swaping water to keep it in check but it is not a complete nitrate cycle ..
The problem with the 3rd and final step is the bacteria that feeds on NITRATE cant servive in a oxegyen rich environment ..

If you build your self a NITRATE REACTOR you can deplete a small amount of water at a time and grow this 3rd bacteria to end the nitrogen cycle..

Basicly a nitrate reactor slows down the water flow to a fast drip.
Then the the first two forms of bacteria that form in the first 1/3 of the reactor use up the o2 (oxygen)..
Then in the last 2/3 of the reator the 3rd form of bacteria can form to end the nitrate cycle..

water at this point needs to be reoxygenated before being put back into a tank a protein skimmer can help to bubble off the nitrogen gas as well as add o2 back into the water...

If your interested in building a nitrate reactor hear is a few links that might help you..

http://archimedes.galilei.com/raiar/denitrif.html
http://w3page.com/fishline/gif/denit.gif?

I built 8 of these for my 1.5 tonne tank and i only do water changes when i want now saves money on salt and water.
My tank cycles every 3 weeks you can watch the nitrate getting slightly higher then it drops by it self as a cycle should ..
 
Thanks for the suggestions and the links, Brovo! I'll definitely keep this in mind as my experience regrows.
 
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