Nitrates going up with carbon dosing

[davidwillis]

My tank is a 300 gallon (fish only right now) tank that has been running for just over a year.
fish:
puffer (porcupine) about 4 in.
powder blue tank: about 4 in
yellow tang: about 2 in
emperor angel: about 4 in
huma trigger: about 3 in
bannerfish: about 4 in
Auriga butterfly fish: about 3 in
sunset buttery fish: about 2 in
flame angel: about 1 in
coral beauty: about 2 in
half black angel: about 2 in
6 damsels

Total fish about 40 inches = 0.13 inches per gallon

Here is what I have for filtration:
I run two klir fleecer rollers instead of filter socks in my sump.
simplicity 320 skimmer
about 20gal of my sump has ceramic Bio media blocks
I have 8L of seachem matrix bio media, which is about 5X as much as they say you need to get your nitrates down (4l in a large reactor, and 4l in a bucket with holes in my sump). These have only been in my system for about 4-5 months.

I did have a small reactor with biopellets (I don't think it was big enough to do much), which I removed when I started with vinegar.

I would like to get my nitrates down. They initially went up over 150 when the tank was cycling, but then went down, and has stayed around 30-50 for the past 6 months.
ammonia <.25
nitrite: 0

I decided to bring my nitrates down, I would start dosing vinegar, and also add micro algae and a turf scrubber. I started dosing vinegar on sep 1 (almost 2 months ago). And I added the macro algae in a section of the sump with a ai refugium light. My macro has been growing like crazy (taking our a handful every couple of days. I also added a surf4x scrubber, which has just started producing.


I am now up to 30ml per 100 gallons (90ml per day on my 300 gallon). However my nitrates are now around 80. I have notices some bacteria strings floating around in my sump, and my class now gets coated with bacteria within 3-4 days. Also my skimmer is pulling out a lot more than it did before, so much so that I had to run a drain line out of the collection cup to the drain so it does not over flow in case I forget to drain it twice a day.

So I am confused as to why my nitrates are going up rather than down. One explanation is that I am dosing too much vinegar, which is growing a lot of bacteria, that then dies off, and converts into nitrate. But I never did see any reduction of nitrate, and I think I will need to end up dosing more than 30ml/100g to bring my nitrates down.

I did notice that my seachem matrix was covered in bacteria (because I was dosing the vinegar next to the pump going to the reactor with matrix in it. So maybe it stopped working due to the bacteria coating it.... So I rinsed it out, and am now dosing the vinegar away from the pump.

I would like to get your thoughts on this, and hopefully figure out how to get my nitrates down.

 

[blaxsun]

Have you tried a commercial product like NOPOX? Other ideas would be some bio-media and a Zeovit reactor.

 

[davidwillis]

Thanks for the reply. I have not tried anything like NOPOX, just vinegar. I have used some bio pellets, but not zeovit. I would like to figure out how to get vinegar to work if possible.

 

[davidwillis]

I know people say dosing vinegar will reduce nitrate, So I am confused as to why it is not working with my tank (and is actually increasing nitrate). I am wondering if I need a bigger skimmer? Or if I just need to keep adding more vinegar? Just wait longer?

 

[Backreefing]

You may have bottomed out your phosphate. If it reads 0 that will limit the reduction of nitrates. I didn’t notice a phosphate number in your post.
Also with those fish corals may be difficult. I have been amazed by corals ability to remove nutrients.
you could do a fudge , or restart bio pellets.
but I’m wondering, why are you going through so much effort to reduce nitrates from 30-50 in a FOWLR tank ? The fish don’t care ?

 

[Randy Holmes-Farley]

I agree that it is worth checking phosphate if you do not already do so.

Is your skimmer working well?

How are you measuring nitrate?

 

[davidwillis]

Sorry, I forgot to mention po4. It is off the charts on my hanna checker. So over 2.0

My skimmer seems to be working good. It is always full of foam, and I had to connect the drain line from the cup to drain it to a drain, otherwise I would overflow in less than a day. Production is much higher after I started dosing vinegar.

I am using an API test for the nitrate. I know it is not the best, and have a Hanna high nitrate on the way. However even though the actual number may be off, I think it can be used to show which direction the nitrates are going.

I would like to get my nitrates down for a couple of reasons. The first is that I would like to have less algae growing on everything (it looks bad). And the second is that at some point I want to add some things that will not tolerate the high nitrate. I don't want to wait until I am ready for something to start getting it under control.

 

[Randy Holmes-Farley]

I suspect random test variability is a likely explanation, as could be a trace of nitrite (not a concern) causing a false elevation of the nitrate reading.

What do you think will not tolerate that level of nitrate?

This tank of Richard Ross has more nitrate and phosphate than you:

Skeptical Reefkeeping 9: Test Kits, Chasing Numbers and Phosphate

By Rich Ross and Chris Jury There are many standard parameters in the reefkeeping world that aquarists strive to match in their home reefs – water quality,

reefs.com

 

[davidwillis]

Wow... That is an amazing tank.... I guess nothing, but I thought inverts, corals, etc would not tolerate that high of nitrate. I guess I was wrong.

Would the Hanna tester also show a false reading with trace amounts of nitrite? My nitrate reads zero, but I am sure there there is a low level undetectable to my test kit.

I would still like to get my nitrates down, if only for me to feel better... So should I just keep increasing vinegar slowly, and be more patient?

 

[Randy Holmes-Farley]

Wow... That is an amazing tank.... I guess nothing, but I thought inverts, corals, etc would not tolerate that high of nitrate. I guess I was wrong.

Would the Hanna tester also show a false reading with trace amounts of nitrite? My nitrate reads zero, but I am sure there there is a low level undetectable to my test kit.

I would still like to get my nitrates down, if only for me to feel better... So should I just keep increasing vinegar slowly, and be more patient?

Yes, the Hannah tester also shows false high nitrate when nitrite is present.

 

[Arego]

I had the exact same problem in a mixed reef for years. I setup an aquamaxx ts2 using prills/ARM and never looked back after 19 days.

It cut no3 by half in our 250g and only got better. I keep the tank at 10-15ppm, could zero it out in a couple days if we felt so inclined. Sorry it isn't a direct answer but your problem was the same as mine. All the best

 

[davidwillis]

I had the exact same problem in a mixed reef for years. I setup an aquamaxx ts2 using prills/ARM and never looked back after 19 days.

It cut no3 by half in our 250g and only got better. I keep the tank at 10-15ppm, could zero it out in a couple days if we felt so inclined. Sorry it isn't a direct answer but your problem was the same as mine. All the best

I have a koralin denitrator. I ran it for a couple of months with no effect. If I slowed the flow down low, it did nothing (if I remember correctly there was still nitrate in the water coming out even at a drip), and then when I would speed it up, it would make nitrite. I also read a lot of people had problems over time with them. So after a couple of months without seeing any results, I gave up on it. Also I knew at some point I would need to clean it, which would start the whole process over again. Maybe I gave up on it too soon, but if carbon dosing would work, it would be supper easy to just adjust my dosage to keep my nitrates where I want them. But for some reason it does not work.... Maybe I just need more patience...?

 

[legionofdoon]

I know that I might be wrong but what if the bacteria is doing the reverse and metabolizing nitrate back into nitrite? I tried dosing nopox, bio pellets and both times my nitrates rose and I had nitrites show up. I stopped and went back to just chaeto and my nitrates dropped from 30+ to around 5-10 in about two weeks. I also have sand, plenty of rock and 5 biobricks and 2 bioplates.

 

[davidwillis]

I know that I might be wrong but what if the bacteria is doing the reverse and metabolizing nitrate back into nitrite? I tried dosing nopox, bio pellets and both times my nitrates rose and I had nitrites show up. I stopped and went back to just chaeto and my nitrates dropped from 30+ to around 5-10 in about two weeks. I also have sand, plenty of rock and 5 biobricks and 2 bioplates.

I am not sure.... I don't have any detectable levels of nitrite (like I did with the denitrator). But I am glad to hear I am not the only one that has seen this happen (nitrates go up). The only things I have read about to watch for is when dosing carbon is bacterial blooms, and cyano. I have backed my vinegar to 15ml/100gal for now. Mainly due to the strings of bacteria I am seeing, and the nitrates going up.