Vinegar dosing only lowering phosphate

[alexander_ktn]

Hi guys and girls,

I have a strange situation at the moment. I started vinegar dosing a few weeks ago because due to housing a few large fish for a friend for a few months I ended up with high phosphates (0.3ppm) and nitrates (10-15 ppm). The fish are now in her tank, so my feeding regime is back to normal.

The vinegar helped a lot with the phosphates, which are now at about 0.02 ppm, but the nitrates strangely haven't moved a bit. I am not sure if I should just continue the vinegar dosing or if I will end up with a phosphate-starved tank and nitrates staying that high... If I had seen any downward movement in NO3 at all I would not hesitate to add phosphate if it became the limiting factor, but as it is now I see no nitrate reduction at all.
Any suggestions/ideas?

Thanks & cheers, Alex

PS: The tests I used are:
PO4: Merck, JBL, Red Sea Pro
NO3: Salifert, Red Sea Pro
so I'm fairly certain the values are in the range mentioned above...

[bertoni]

If you have a nitrite test kit, getting a reading might be useful. Nitrite will confuse nitrate test kits. Having high nitrate is fairly common, though. I would continue the vinegar dosing for a while to see what happens, personally, since the tank seems to be benefiting from it. I would watch for signs of overly low nutrient levels, though.

[alexander_ktn]

Thank you, Jonathan! I'll continue and hope the nitrate goes down... ;) I'll definitely report back what happened...

As for nitrite: I have so many test kits but nitrite is not among them... I reckoned I shouldn't have any measurable nitrite in the water since I use ozone in that tank and nitrite should be practically immediately oxidized to nitrate. I didn't mention it before since I didn't think it important for the effect of the vinegar dosing - sorry. I don't use it anywhere near bactericidal levels, just to remove potential yellowing compounds.

[bertoni]

Ah, okay, I suspect the nitrite level is zero, then. :) Sounds like a fine plan to me. :)

[triggreef]

I would keep it exactly as is. Thats the number I chase, but seldom achieve for po4 and I like nitrates. They dont hurt anybody.

[tmz]

There are a number of reports of it taking longer for the nitrate to go down than the phosphatewhen usingvoka or vinegar.
It may be that the bacteria consuming the extra organic C take their N fro m ammonia directly along with the phosphate and nitrate reduction has to wait for anaerobic activity . This is a possible scenario noted in one study. If so, the nitrate , goes down eventually because less is produced as the N from the ammonia that forms nitrate is limited but the nitrates already there are slow to brakdown. It it takes months sometimes to see the nitrates fall. FWIW , I have better success , reducing the nitrates by other means at the star of the process and then using the acetic acid to maintain low levels.

[alexander_ktn]

I would keep it exactly as is. Thats the number I chase, but seldom achieve for po4 and I like nitrates. They dont hurt anybody.
I am not one to chase zero nitrates or phosphates, but something in the range of 0.5-3 ppm of NO3 is what I usually try to maintain in my tanks and feel the corals look a bit better with. With the current values I have a few corals that have become a bit browner than I like them to be. It could also have been caused by the combination with the initially higher phosphate value of course, since it's only a few weeks that I started carbon dosing. I'll see how the tank develops.

There are a number of reports of it taking longer for the nitrate to go down than the phosphatewhen usingvoka or vinegar.
It may be that the bacteria consuming the extra organic C take their N fro m ammonia directly along with the phosphate and nitrate reduction has to wait for anaerobic activity . This is a possible scenario noted in one study. If so, the nitrate , goes down eventually because less is produced as the N from the ammonia that forms nitrate is limited but the nitrates already there are slow to brakdown. It it takes months sometimes to see the nitrates fall.
Ah, thanks for the explanation - so there is hope yet. :)

FWIW , I have better success , reducing the nitrates by other means at the star of the process and then using the acetic acid to maintain low levels.
The tank in question is my office tank and has no sump, so any additional equipment would need to go into the display tank... Thus vinegar seemed the best "no equipment, no hassle"-option, especially since both nitrate and phosphate seemed to me to be quite balanced in the beginning for carbon dosing (despite being high).

For the moment I will continue dosing and testing often and see what happens.

[Buzz1329]

Based on what I've read and in my limited experience, it takes some time for vinegar to bring the nitrates down. I've been dosing it in my 180 for 4+ weeks, gradually increasing the daily dose from 20 ml to 75 ml. I started using it because my nitrates were too high (20 ppm), even though phosphates seemed low (undetectable with Salifert and Red Sea kits). My nitrates stayed at 20 ppm until yesterday, when they dropped to 10 ppm. Still a ways to go, but I hope I have turned the corner.

Good luck

Mike

[tmz]

It seems to happen like that. No movement then a big drop. Then no movement for weeks then another.

[121]

This happened to me with vodka dosing. I had to add sodium phosphate which the bacteria need in order to consume the nitrate.

[alexander_ktn]

As promised a short update: the nitrates are definitely slowly moving down (hard to tell exactly with the nitrate test kits, but the color got lighter).

I increased the vinegar dose slightly and to prevent phosphate from being the limiting factor fed some lobster eggs (afaik very phosphate-heavy) in addition to my usual feedings.

I did get some heavy breathing fish for 2-3 hours after I dosed too much vinegar one day - not going to do that again...

So thank you again - and I will report once my nitrate is in the 1-2 ppm range.

[bertoni]

Okay, that's good progress. :)

[alexander_ktn]

Another update: Success! ;)
Nitrates went down really fast in the last couple of days, so that I am now at about 1-2ppm, phosphate is also low.

I also started using a slower dosing method - pretty low-tech:
A plastic cup with a pinhole in the bottom is placed on the corner of the tank and drips a mixture of tank water and vinegar into the tank over the course of about an hour. I switched to this method since one of my maxima clams curled up its mantle when it got hit by a flood of vinegary tank water...

[tmz]

Glad you are having some luck with it.

The undiluted vinegar is best dosed slowly during periods of photosynthesis . The low pH from the 5% acetic acid in it keeps the bacteria from consuming it before it goes into the tank. The slow dosing limits the the precipitous initial pH drop it causes when dosed in bulk.