CANNOT get nitrates down

[MacDime]

Firstly, I have 60 cube sps tank with a 29 gallon dump. Psk75 skimmer, jabeo DC return pump, jabeo dosing pump, Jabeo wp40, korallia 3 ph.

For the past month and some my nitrates have spiked heavily (50-100 salifert test). I do weekly 10 gallon water changes regularly. I've been doing more since the spike. Recently I've done 50 gallons of water changes this week and they still are testing high nitrate. 2 weeks ago I started using Red Sea no3po4x as a source of carbon dosing. My skimmer cup is filling daily.

I have not had any fish or invert deaths. No overwhelming algae, just some red slime. I removed the sump and thoroughly cleaned it to remove any detritus that might have been missed. It's clean as a whistle now. I only have 4 fish, an anthias, a juvenile sailfin, 6 line wrasse, clown. 2 shrimp and a few snails. I only feed them a few pellets once a day. I have a thin sand bed, maybe an inch. I have plenty of live rock. The tank has been running for 7 months but the rock and live stock I've had for a few years.

Can someone please give me a clue of where this nitrate it coming from.:mad:

[jrr98002]

Have you tried a different test kit? Your bioload isn't that high and with those amounts of WCs, I would suspect you might be getting bad readings from a bad kit. Other than that, someone else will have to chime in.

[TigeBell]

I am assuming you are using an RO/DI unit. Are you testing that water? When was the last time you changed the filters in that unit? Just bring up ideas.

[MacDime]

I am using RODI water, using the same test kit, it has read negative for nitrate. I changed the filters earlier this year around March. As far as testing the tank water I would believe it is high because the skimmer is cranking out skimmate and the polyps on acros are definitely not extending much anymore.

[RobZilla04]

Have you used a siphon on the sand bed during water changes?

If not, don't start by doing the entire tank at once. Do a third thoroughly and on each subsequent water change do another third until you have got it all.

[mcgyvr]

My $0.02..
That skimmer is undersized for your tank..

Nitrate reduction via carbon dosing,etc.. does NOT happen over night and can take weeks to months to work well.. Its not magic.. And an undersized skimmer is NOT helping that..
The skimmer is imperative so you get that excess of bacteria created by the carbon dosing out of the water..

Theoretically a 50% water change "should" drop nitrate levels by ~50%.. You stated a before reading but didn't state an exact "after" reading.. Did it go down ~50%?

A "thin" sand bed really doesn't give much of a chance for anaerobic bacteria/areas..
The rock "can" if its the right rock (porous,etc..)

You have a "fairly" small amount of water so keep going on the water changes and see how that works.. Do 50% once a week or 30%.. Basically as much as you can and see how that goes..

But so far there is no "magic" in a bottle or "magic" rock or other magic products.. Nitrate elimination (conversion to gas,etc..) is the toughest process to happen in our tanks.. Ammonia to nitrate is simple..

oh and did I hear "filters".. You "might" want to try taking that offline and see how it goes.. In general mechanical filtration has been given the term "nitrate factories" around here due to lack of frequent maintenance,etc..

[Dan_P]

I don't understand why the large water change did not result in a large dip in the nitrate level. I suspect the test kit, but I am under the impression that the kit would fail by showing low not high nitrates. Still, something to consider.

I have nitrate spikes when my macro alear dies back. It then takes at least a month for the nitrates to come back down to non detectable. Last one peaked at 10 ppm. So, patience is definitely in order, even carbon dosing takes time to have an impact.

If you haven't been taking weekly nitrate readings, this nitrate level increase may have started further back than you think.

[neiltus]

Salifert NO3 kits also pull amine nitrogen into their test whereas other kits do not.

I can test my tank for NO3 with two tests, and I generally get two different readings.
Salifert -25ppm
Nyos - <12ppm

Soooo, that might have something to do with your numbers.

[RobZilla04]

When you clean the test vial are you leaving any tap water residue behind? I ensure that I dry everything with a clean paper towel after testing.

[Bananafish]

My $0.02..
That skimmer is undersized for your tank..

Nitrate reduction via carbon dosing,etc.. does NOT happen over night and can take weeks to months to work well.. Its not magic.. And an undersized skimmer is NOT helping that..
The skimmer is imperative so you get that excess of bacteria created by the carbon dosing out of the water..

Theoretically a 50% water change "should" drop nitrate levels by ~50%.. You stated a before reading but didn't state an exact "after" reading.. Did it go down ~50%?

A "thin" sand bed really doesn't give much of a chance for anaerobic bacteria/areas..
The rock "can" if its the right rock (porous,etc..)

You have a "fairly" small amount of water so keep going on the water changes and see how that works.. Do 50% once a week or 30%.. Basically as much as you can and see how that goes..

But so far there is no "magic" in a bottle or "magic" rock or other magic products.. Nitrate elimination (conversion to gas,etc..) is the toughest process to happen in our tanks.. Ammonia to nitrate is simple..

oh and did I hear "filters".. You "might" want to try taking that offline and see how it goes.. In general mechanical filtration has been given the term "nitrate factories" around here due to lack of frequent maintenance,etc..


Undersized skimmer + carbon dosing = more nitrates than when you started.

[mcgyvr]

Undersized skimmer + carbon dosing = more nitrates than when you started.
Entirely possible..
I find you hit that bacterial "snot" problems before that though..

[mcgyvr]

I suspect your nitrate levels were higher than you though.. above the range of the test.. So you simply didn't notice the drop..
If it was 200 it may now be 100 and still showing the same on the test.. (I'm not sure of the range of the test you are using)

Keep at it man.. You can do it..

[Dan_P]

[QUOTE=neiltus;24851172]Salifert NO3 kits also pull amine nitrogen into their test whereas other kits do not.[/QUOTE

The reaction involved in these test kits involves reducing nitrate to nitrite which is then reacted to give a colored species. The presence of nitrite, not an amine, can result in high nitrate readings.

[MacDime]

thanks for all the input. I added a larger skimmer on my tank that i had on a frag tank. Hopefully with that and continuing water changes, the nitrate should go down. I didnt think about how starting carbon dosing would react to adding nitrate in the tank at the begging of use.

[pisanoal]

What do your acros look like? I suspect they would be completely brown if not dead with 100 ppm nitrate... If they still have color, that test kit is most likely to blame, or nitrite like someone else mentioned, although that is hard to believe on an established tank with no die off. Really hard to believe that large water changes have no immediate impact. Are you testing an hour or two after? Or a day after? When you do your next water change, test the mixed saltwater before you put it in the tank for a baseline. Also recommend another test kit for a second opinion.

[MacDime]

What do your acros look like? I suspect they would be completely brown if not dead with 100 ppm nitrate... If they still have color, that test kit is most likely to blame, or nitrite like someone else mentioned, although that is hard to believe on an established tank with no die off. Really hard to believe that large water changes have no immediate impact. Are you testing an hour or two after? Or a day after? When you do your next water change, test the mixed saltwater before you put it in the tank for a baseline. Also recommend another test kit for a second opinion.

Well I did a 50 gallon water change today. Tested the water about 8 hours later and the nitrate did go down. Still shows up around 25 but with the larger skimmer my hopes are high. My acros colors still look good except for one that is definitely browning up.

[mcgyvr]

There ya go... Water changes are working nicely.. Just keep at it..

[Rybren]

You should also note that there seems to be an issue with the colour cards in the Salifert Nitrate test kits. There is a huge difference in the colours between the new test cards and the older ones.

Habib, the owner of Salifert, acknowledged that it looks like there may be an issue and has stated that he has not changed the formulation of the test kit enough to warrant the difference in colours on the new cards. A problem with the printer was suspected, however Habib has stopped posting and replying to PMs, so it was never confirmed.

I tested a 10 mg/L Nitrate reference sample using my Salifert kit and it produced a reading of close to 50ppm. Most of the other colours read higher than the older test kit.

You may want to try using a different brand of kit to see what you get. On my tank, Salifert shows close to 50ppm; API and Seachem both show under 10ppm.

[MacDime]

after a large water change and adding a larger skimmer, that nitrate has gone down and held. Now my alkalinity is out of whack so I have a new problem I have to figure out. but I believe the red sea No3Po4x is starting to work. I tested on the api kits as well and they are showing low nitrate. So I think I'm in the clear for now

[kecked]

If you are ever in wonder if the nitrate will go down with a water change. Dilute the tank water as the new water would and test. That will tell you the water change volume you need. example 50% change =50 reduction so 50% dilution with DI should give 50% change. Now try the test kit. If it still reads weird the test kit is the problem.

[MacDime]

If you are ever in wonder if the nitrate will go down with a water change. Dilute the tank water as the new water would and test. That will tell you the water change volume you need. example 50% change =50 reduction so 50% dilution with DI should give 50% change. Now try the test kit. If it still reads weird the test kit is the problem.

That's a very simple, but effective idea! Never thought of that