Vodka dosing not kicking in...am I doing it wrong?

[boobookitty]

Started a 400G tank about 2.5 years ago, and it's been successful, but from day 1 I had measurable phosphates and nitrates that have gotten worse and worse. I had a lot of success with zeovit on my previous 240G tank, so I started off using that, but the phosphates and nitrates climbed steadily, so I finally gave up on zeo; to be fair, this tank is stocked quite a bit more than the 240G, including 9 tangs, 6 angels, and a lot of smaller fish.

So in December I switched to vodka dosing. At that point the nitrates were at around 50 (hard to tell sometimes with Salifert kits), and phosphate was at around 1.35 according to a Hanna colorimeter. I started slowly as recommended in the Walton/Bjornsen article in Reefkeeper. It's a 400G tank, so it has taken a long while to get to decent dosing levels; took until February to get to 11ml a day, with of course no change in nitrates/phosphates. I started raising it half a ml every other day, then half a ml every day, then a ml a day. By April I was up to 33ml a day, and now I'm at 47ml a day.

And still no change. Or at least not much: this morning phosphates measured 1.25 instead of 1.35, but it's always fluctuated a bit. Should I get more aggressive with raising the dosing? Is there a "target" number for a decently stocked 400G? It's been a frustrating 6 months of "easing" into this...

[bertoni]

I'd keep raising the dosing as long as the tank shows no signs of bacterial blooms (hazy water, slimy coatings). You could add 25% per week, or even more frequently, for a while.

[boobookitty]

Wondering if there’s a target. I thought once I got to 40ml a day I’d see results. 60? 75? Totally different from tank to tank?

[bertoni]

Totally different from tank to tank, unfortunately.

[ramseynb]

You might try looking into vinegar instead of vodka. I've heard people prefer it. I'm still on the ZEO train though so I can't say one way or the other.

[bertoni]

Vinegar seems to cause less cyanobacteria for some people, but not always.

[ramseynb]

I imagine it's probably cheaper too. Just a guess though.

[Dan_P]

The published dosing charts have been incorrectly scaled up from the day they were published. As the number of gallons increases in the chart, the recommended dose decreases per gallon of aquarium water. You can see how large the error is by comparing the last entry of the 25 gallon column to the last entry for the last column. This is one possible reason for the difference in nitrate reduction you are experiencing.

Another possible reason “for no two tanks behaving the same” is the bacterial population, both the number of bacteria and diversity of species. A totally unstudied, terra incognita of knowledge for aquarium carbon dosing.

Another substantial area of ignorance surrounds the impact of other nitrogen containing compounds on nitrate consumption.

And finally, knowing when the system becomes sufficiently nitrgen starved for bacteria to start consuming nitrate, possibly their least favored nitrogen source, is never discussed.

All these factors contribute to the need to “titrate” the daily amount of carbon dosed to the aquarium to achieve the desired outcome.

[ClownNut]

do you have sand?
last time i vodka dose, i had sand, it took a lot more and a lot longer than the chart in order to get my nutrient to goes down, i dont know why. it just did. i think i noticed my nutrient start to drop, from day 1 was about 6 months. i keep increasing the amount as recommended by the chart until I started to see the drop.
i talked to Matt.B about it too, he told me just keep going until you see the drop. it's nice he was local at the time.

[boobookitty]

Yah, I've just been steadily increasing dosage. Don't want to switch to vinegar; can't imagine the quantity I'd need if close to 50ml a day of vodka hasn't had a result yet. There's no need to "seed" the tank with a specific bacteria that I might be missing, is there? Nothing I'd read in the vodka dosing method mentioned that.

Upped it to 49ml today. My tank drinks more than I do now...

[Dan_P]

Originally Posted by boobookitty

Yah, I've just been steadily increasing dosage. Don't want to switch to vinegar; can't imagine the quantity I'd need if close to 50ml a day of vodka hasn't had a result yet.

The conversion usually goes something like this. 80 proof vodka is 40% ethanol. Vinegar is 5% acetic acid. Both have two carbons, so, they are basically interchangeable (more below on this assumption). 40% / 5% = 8, which is the factor to increase the volume. For example, 50 mL of 80 proof vodka is 400 mL vinegar.

About the equivalency assumption. It’s an approximation. In terms of the amount of carbon, 1 g of ethanol provides 24/46 or 0.52 gram while while 1 g acetic acid delivers 24/60 or 0.40 gram. The other approximation no one discusses is that acetic acid is more oxidized than ethanol and cannot supply the same level of energy nor the same molecular fragments as ethanol. The level of the impact of these differences has not been discussed but I wonder if it is the basis for cyanobacteria not being able to use acetic acid.

[boobookitty]

Since I can autodose vodka twice a day, the idea of having to manually add 400-600ml of vinegar every day is anathema ,

[Big E]

You can try seeding with some MB7 and see if that speeds up the process. Back in the early days of vodka dosing one of the most successful systems was SunnyX and he used vodka and MB7 in combination.

This is basically what all the commercial systems do. There is a bacterial supplement combined with carbon dosing.

Follow the directions on the bottle.

[josephxsxn]

I did the vodka thing for a while and never felt like it did enough.

Switched to a sulfur denitrator and said goodbye nitrates. After a case of vodka the denitrator is more cost effective. I built my own, when I started I had nitrates over 50ppm going into it, after the denitrator matured water comes out 0ppm. Today my nitrates are under 4ppm (red Sea nitrate test, I do the high range test). It can take a few weeks for your reactor to grow enough to be useful and noticable.

[boobookitty]

(sigh) So I got up to 51ml/day, and lo and behold phosphate started dropping, from the static 1.35 to 1.1, then down to 0.95. But then it went back up in a day to 1.18 and has been stuck there for 2 days. Still increasing vodka daily (up to 54), but is this normal, or should the progression down be steady once it starts?

[Dan_P]

Originally Posted by boobookitty

(sigh) So I got up to 51ml/day, and lo and behold phosphate started dropping, from the static 1.35 to 1.1, then down to 0.95. But then it went back up in a day to 1.18 and has been stuck there for 2 days. Still increasing vodka daily (up to 54), but is this normal, or should the progression down be steady once it starts?

Just some thoughts...

- Phosphate level may not be constant throughout the day. Best to test same time every day.

- The phosphate changes seem large enough to say they are real and not noise in the data, but without running a triplicate test, who knows.

- I have run three small scale dosing experiments now and all three showed a rapid decline in nitrate concentration at some point. I am trying to determine what that “point” is. Amount of carbon, time, both, something else, all of the above. Phosphate level doesn’t seem important. All samples had undetectable PO4, but that is still enough for bacteria I suspect. I wonder whether the oxygen level is a factor.

I am following

[bertoni]

I might keep increasing the dose. Is the feeding schedule stable? I agree that testing at the same time of day might make some difference, although those changes are reasonably large.

[boobookitty]

I always take my measurements in the morning between 8 and 9 (phosphate, alk, etc.). I’ve continued increasing dosing - up to 55ml today - but this morning phosphates were back at 1.36. Although to be fair my fuge light apparently has been off for 2 days (fixed it this morning) so that may have played into it. Just frustrating to be 6 months into dosing with zero appreciable change.

[Dan_P]

Are you using 80 proof vodka?

[boobookitty]

Yes, standard 80 proof.

[boobookitty]

(sigh) This whole thing is ridiculously frustrating. I'm at 7 months of vodka dosing now, with a daily dose of 102ml, and last week it looked like it was *finally* kicking in. Phosphates hovered at around 1.15 for months, then dropped overnight to 1.10, then 1.05, then to 0.98. "I'm on my way" I thought.

Then two days ago they rose to 1.01, then 1.05 yesterday, then back to 1.15 today.

Is this up and down crap normal? Before anyone asks, nothing else has changed. I'm increasing dosing by 2ml a day now, and I'll keep doing that, but it's frustrating to be back to 1.15 when I was under 1.0 a few days ago...

[fijisrfr]

It can be frustrating, personally, I’ve started the program a couple of times but it always ended up.....
10ml for the tank then 100 ml for me!
I know this won’t help but just wanted to put out there that there is a detrimental effect if you don’t follow the schedule!


Sent from my iPad using Tapatalk

[boobookitty]

Understood, but I can deal with a bacterial bloom. I don't think the schedule took into account large tanks with a bad problem...if I had followed it, it would have taken me 3.7 years to get up to 100ml a day.

[bertoni]

Those numbers are close enough together to be in the noise, given testing limitations and even fairly small variability in feeding levels. Personally, I don't think the dosing is going to "kick in". I'd either increase the dose or look for another approach. Are there any signs of bacterial slimes or issues with coral health?

[boobookitty]

The dip was pretty steady over a couple days, then steadily rose back up. It was the equivalent of about 20%, which given the pattern seemed significant. I’m still increasing dosing 2ml a day. No bacterial bloom or slimes. I have had a weird problem with acros, but it predates the dosing and I’ve been waiting until phosphates and nitrates are down to try to address it since such high levels doubtlessly interfere.