Help with Nitrate problem

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Poekin

Gambusia
MFK Member
Oct 17, 2008
154
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Baltimore, Maryland
This is a 75 gallon lake tanganyika tank. Most of the fish are pretty small, i don't think it is over stocked. I have a total of 15 fish, maybe 30" of fish in total so i don't think i am breaking the 1" per gallon rule.

The tank is completely overfiltered.
I run an eheim 2028
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3579+3580+10946&pcatid=10946

and a Drfostersmith hang on back filter. Its the model 55 seen here:
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3579+3608+16729&pcatid=16729

I also have a bag of seachem purigen in the canister filter.

I am trying to keep my water perfect. But i just can't seem to keep my nitrate down below 20ppm. The highest i've tested is about 40ppm. For example, yesterday i did a 50% water change and tested my nitrates again today and they are still 20ppm. What can i do differently? I am thinking of adding some of Seachem de-nitrate. I can't imagine making more water changes... and frankly i am afraid to.

I already do 2 50% changes a week. When i add my water i am sure to add a capful of Prime as well as some Lake Tanganyikan salt. Any suggestions??
 
First off, don't go by the 1" per gallon rule, it doesn't work...:)

First I would check your tap water for nitrates, you are adding fresh water that already has nitrates in it you are limiting the effectiveness of lowering nitrates.
20ppm of nitrates isn't that bad to maintain, I wouldn't really worry if you can't maintain below that.

Burt :)
 
How long has the tank been setup? Did it cycle fully ? How much bio. filtration do you have? Have you added new fish lately?
I had elevated nitrate readings after a year and it was because my little fish had grown into big fish,put in some more scrubbies and all is well now..
 
The Nitrates come from the nitrification of organic materials. This can be organics from fish respiration and digestion or the aerobic breakdown of substrate materials and trapped poop/uneaten food. Ammonia becomes Nitrite becomes Nitrate.

You can reduce it on the source side by making sure the tank is clean and possibly reducing the amount you feed.

You can get rid of it a few different ways.
1. Water Changes.
2. Grow plants.
3. Anareobic Bacteria.
4. Exotic methods.
5. Chemical Methods.

You are already doing #1. If your nitrate is 40ppm and you do a 50% wc with *clean water, then your nitrates should drop to 20ppm. The next 50% would make it 10ppm..

Number 2 might be an option.. Are you stocking any plants? If not, would you consider some or an algae "filter"? It's a perforated sheet with a lot of surface area under bright lights you trickle the tank water over. Plants absolutely love Nitrate.

#3 is probably impractical but I'll mention it anyway. If you very very very slowly (drip)(drip)(drip)(drip) water into a semi-enclosed vessel filled with rocks, sand, and gravel it will develop anaerobic bacteria that eat Nitrate. It will also make Hydrogen Sulfide so you have to degas it before it goes back in the tank. The aquaponics folks make these and stuff in a layer of rusty nails to increase the iron levels available for plants.

4. Exotic Methods.. Ion exchange? run the pH to 10, offgas the Nitrate, and adjust it back down to 7 before returning it to the tank? These are pretty much impractical vs. adding plants.

5. Zeolite in the eheim? You can recharge it a number of times, so it isn't that expensive.

A couple of out of the box answers come to mind.
Could your test kit be bad? Imho, test strips _suck_. If your stuff is old it could just be misleading you.

* If your tap water is treated with Chloramine then that may be the source of your extra ammonia. http://en.wikipedia.org/wiki/Chloramine

-ellie

Warning: I am not an aquarium person, nor do I play one on tv. My Tilapia are patiently waiting for April when I can hook our aquaponics system back up..
 
the only way more biofiltration would decrease nitrates was if it formed anaerobic conditions that completed the nitrification process back into a gaseous form. It can work, but it can also have disastrous effects if the produced hydrogen sulfide is released back into the water column.

I agree with nitrates being in your tap water, a lot of water systems have elevated amounts.
 
I tested my tap water and the nitrates are reading at 0ppm. I believe my test kit is ok... its pretty new and its the API test kit. I also use the jungle quick dip tests, which are telling me the same thing.

I am considering adding some floating, lily type plants to soak up some of the nitrates. Any suggestions?

I am also considerind adding the seachem de-nitrate stuff. Is this a good move?
 
meh, it will work. Just remember that your fishes health will be relying on a resin that you have change/prime every month or so.
 
You might also look at your feeding regiment. Are you feeding to much. Are you gravel vacing with these water changes?
 
I'm gravel vaccing. Here is my tank:
IMG_1349.jpg
When i gravel vac, i pick up as many rocks as i can. But i can't reasonably dismantle and reassemble the big part of the rockscape each time. I usually just do my best to clean around it. Perhaps this is the source of my nitrate problem? My solution to this is to buy some aquarium epoxy soon and start to slowly work my way down from the top, glueing each rock together. I figure this way i can keep the formation, but have it be in 3 or 4 large chunks that are easier to take out of the tank and clean under.

As for feeding... over feeding could be a problem? My fish are really small, i feed them a pinch of NLS growth 2-3 times a day. It seems as though they eat most of it. Sometimes when i vacuum though i can see there is some caught in the crushed coral.
 
Hi.

I did some digging and I was wrong about the Hydrogen sulfide. That comes from dying and decaying aerobic baceria. A properly functioning Anaerobic filter only makes N2, which is harmless and offgassed into the atmosphere.

My confusion came from UVI's aquaponic system that uses 4x4x4 tanks stuffed with bird netting for Total Suspended Solids control and _those_ make the H2S gas.

My apologies..
-ellie
 
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