Hydrogen sulphide - major frustration- what am I doing wrong

[CalicoCellars]

Hey folks; am facing some H2S issues even with Sensy yeast; which is supposed to be a low sulfide yeast. This is in 10 gallons Sauvignon blanc juice. Didn’t get the chance to get YAN measurements but maybe the juice didn’t have additional nutrients

Is there a risk of adding too much yeast nutrient? Is there a threshold? I have heard that the main thing to worry about is potential for microbial spoilage during aging but I am intending the white will only be for 2 years tops and sulfite can also control this, right?

Thanks in advance for any guidance

 

[Ohio Bob]

Hey folks; am facing some H2S issues even with Sensy yeast; which is supposed to be a low sulfide yeast. This is in 10 gallons Sauvignon blanc juice. Didn’t get the chance to get YAN measurements but maybe the juice didn’t have additional nutrients

Is there a risk of adding too much yeast nutrient? Is there a threshold? I have heard that the main thing to worry about is potential for microbial spoilage during aging but I am intending the white will only be for 2 years tops and sulfite can also control this, right?

Thanks in advance for any guidance

Is this from a juice bucket? I would assume the YAN would be close, as the SG and pH are usually pretty good.

Did you ferment in an open bucket, where the yeast has access to lots of oxygen? Yeast can be stressed by not getting enough oxygen.

 

[winemaker81]

Hey folks; am facing some H2S issues even with Sensy yeast; which is supposed to be a low sulfide yeast. This is in 10 gallons Sauvignon blanc juice. Didn’t get the chance to get YAN measurements but maybe the juice didn’t have additional nutrients

Is there a risk of adding too much yeast nutrient? Is there a threshold? I have heard that the main thing to worry about is potential for microbial spoilage during aging but I am intending the white will only be for 2 years tops and sulfite can also control this, right?

Thanks in advance for any guidance

Folks speak of thresholds for too much nutrient, but I can't recall any hard figures.

I go by package direction on the nutrient, and if a strain has high needs, I add 50% more.

At this point you have H2S, so you need to act immediately. The longer it's present, the worse it gets. Add a dose of K-meta, and stir the heck out of it. Do this in a well ventilated area and run a fan -- the reek gets worse as you stir to release it from the wine.

Following are my notes from a 2020 second run wine, which had bad H2S. I had to go as far as adding Reduless to it. I've had it twice since then, but caught it early enough that K-meta and stirring addressed it. Since then I'm paranoid about H2S and ensure I have sufficient nutrient added.

https://wine.bkfazekas.com/2020-red-blend-second-run/

EDIT: the original post had too low a dose of K-meta. No idea what I was thinking, but it's fixed now.

 

[CalicoCellars]

Is this from a juice bucket? I would assume the YAN would be close, as the SG and pH are usually pretty good.

Did you ferment in an open bucket, where the yeast has access to lots of oxygen? Yeast can be stressed by not getting enough oxygen.

Was a juice bucket and with open top. i dunked a wort chiller in there with my ghetto glycol chiller made from a hacked up air conditioner and put the lid over. Added goferm protect at the start per recommended dosage and full dose of Fermaid-O at pitching of yeast; added Fermaid K at like 18 brix; and using sensy yeast, which is supposed to be low H2S; it kept fermenting and a few days later I added more DAP after i detected the smell; fermentation is finished (~-1 brix) and I Splash racked this morning to new vessels, and ordered Reduless for overnight delivery.

I had taken a gallon from each of the two 6 gal juice buckets in a 3 gal carboy to get headspace for AF, and that carboy with almost the same nutrient regimen has not produced the smells. that one was at a higher temperature because i was swapping buckets of frozen water bottles in a Tupperware about twice a day to keep it relatively chilled (and after 4 days of this i got busy/lazy and stopped hauling the bucket up the starts to and from the garage freezer). Maybe the temperature was too cold for the sensy yeast? i kept my glycol chiller at around 55F - 57 F; these yeast say their range is 54-64F; but, perhaps immediately adjacent to the coils it could be colder and in the bulk liquid it could be warmer;

I will take the advise on setting up a box fan as soon as i get back tonight and dosae with more kmeta and splash/degass some more.

Will definetly be on the fermaid-K train as i am not sure if the Fermaid-O did enough;

can always go get some frozen SB buckets and try again when i am not also deailng with all the other fermentations simultaneously; but will try and save it. i have copper sulfate on hand; still very cloudy so i may treat also with Bentonite and Sparkelloid to see if floculating the yeast garbage and racking off helps the issue from recurring in bulk aging.

Thanks for the assist; i'll keep the thread posted. Going to read the link to the 2020 batch you sent now!

-Mike

 

[BPL]

Hey folks; am facing some H2S issues even with Sensy yeast; which is supposed to be a low sulfide yeast. This is in 10 gallons Sauvignon blanc juice. Didn’t get the chance to get YAN measurements but maybe the juice didn’t have additional nutrients

Is there a risk of adding too much yeast nutrient? Is there a threshold? I have heard that the main thing to worry about is potential for microbial spoilage during aging but I am intending the white will only be for 2 years tops and sulfite can also control this, right?

Thanks in advance for any guidance

For the future.....Adding too much nutrient? IMO, yes. I have no idea what the threshold is. I do know this: Adding too much Fermaid will give a mineral taste. Adding too much standard yeast nutrient (containing Urea) runs the risk of potential really bad nasties in the wine. Too much DAP (alone) will almost likely cause too much cell activity and heat. Too much DAP produces some bad tasting wine. Adding nutrients at the wrong time, as in late in the fermentation, runs the chance for spoilage.

Measuring YAN and using a reliable calculator to supplement nutrients is absolutely the best. If that is not possible (like for me) is use the FermCalc YAN calculator app and enter the starting YAN at 150. The calculator takes care of the yeast demand.

Right or wrong, I've made some pretty darn good wines following the FermCalc app method.

I hope this helps going forward.

 

[CalicoCellars]

For the future.....Adding too much nutrient? IMO, yes. I have no idea what the threshold is. I do know this: Adding too much Fermaid will give a mineral taste. Adding too much standard yeast nutrient (containing Urea) runs the risk of potential really bad nasties in the wine. Too much DAP (alone) will almost likely cause too much cell activity and heat. Too much DAP produces some bad tasting wine. Adding nutrients at the wrong time, as in late in the fermentation, runs the chance for spoilage.

Measuring YAN and using a reliable calculator to supplement nutrients is absolutely the best. If that is not possible (like for me) is use the FermCalc YAN calculator app and enter the starting YAN at 150. The calculator takes care of the yeast demand.

Right or wrong, I've made some pretty darn good wines following the FermCalc app method.

I hope this helps going forward.

Thank you for this. I had the FermCalc app on my phone but did not realize there was a YAN calculator in the Miscellaneous tools subsection. I will use this going forward 100%.

It seems the Vinmetrica YAN kit (which i have but ran out of time/energy to use ahead of AF) is mostly a (relatively) simple titration, with a lot of reagent prep. The use of formaldehyde and some of the centrifuging/decanting/filtration as recommended in the method does take some setup in terms of capability; is there a simpler way to conduct YAN measurements? i have seen some stuff about spectrophotometry but I think that may exceed my budget at this moment;

This year I think the biggest stressor I had is once I get all the crushed fruit and such, and get it back to the basement, I feel like I'm on the clock for getting all the lab results before I risk wild fermentation; I measure initial gravity, pH, temperature, Free SO2, TA - and this year I had to press the Chardonnay (in addition to the Tempranillo Rose after a short skin contact) since the white wine dedicated press was not working at the grape supplier for whites. I was perhaps a bit too ambitious and started 6 separate batches on the same weekend (108 lbs Cabernet Sauvignon, 108 lbs Merlot, 180 lbs Tempranillo (part rose for Rosado, part red), 108 lbs chardonnay, and 12 gallons sauvignon blanc juice). It's just me and my wife, but we had my brother and sister in law's help with transporting the fruit, pressing, cleaning, sanitizing, titrating, pH measurements, etc.

While presently I don't have a large enough refrigeration capacity to cold soak everything for a day or two, I do toss sanitized frozen water bottles and jugs into the must buckets to try and stave off spontaneous ferments and get a pseudo cold soak for as long as possible. This can buy a bit of time to do the extra lab work. I have one 21 cubic foot upright garage refrigerator but this will only handle maybe 2 carboys of 5 or 6 gallons each.

How do you all generally manage the #HurryUpAndWait phase of the initial influx of fruit ready all around the same time? I have to find a way to make it less stressful next year; it's far too much. (a mess of my own creation, I fully realize).

How fast generally do the lab results come back for YAN from contract labs like ETS? I would consider sending out the juice to a lab if I could keep the remaining must cold while I wait for results, to delay fermentation initiation; but I'm not sure if my supplier for grapes (Corrados in Clifton NJ) would allow me to store the grapes in the walk in, crush a few, send a sample, wait some days, then pick it up. I suppose I could ask them, and or in the future try and find suppliers who provide the YAN on the fruit ahead of the sale in Northern NJ area (Or Eastern PA, or NY State but transporting the fruit 4-5 hours from the finger lakes in my little Honda fit is also a no - go, lol) but I don't know of any ones local to us.

Do you all have any grape source recommendations who do the must analysis ahead of the current year's harvest? I know of Delta Packing, but the quantities seem to be pretty high for minimum orders. Closest so far I found is Fulkerson's on Seneca Lake in NY (Finger lakes) about 5.5 hours drive https://www.fulkersonwinery.com/juice/. The whites especially Riesling would be good to try once but the reds in this region struggle to reach full morphological ripeness and tend to be thinner; which is not our more preferred style.

Thanks for the assistance and helpful information; I have bookmarked ETS to look for lab analysis; if it saves batches, it's worth the cost.

 

[BarrelMonkey]

Thank you for this. I had the FermCalc app on my phone but did not realize there was a YAN calculator in the Miscellaneous tools subsection. I will use this going forward 100%.

Scott Labs also has a useful yeast nutrition planner. My usual go-to regimen is 20g/hL FMO at ~3 brix drop and another 20g/hL at ~1/3 brix drop. This year I doubled up on one of my fermentations (ie 40g/hL + 40g/hL) since I was using a nutrient-hungry yeast (BA-11). Still in the last few days of fermentation but it all tastes great so far. I would definitely not add any nutrients once below ~10 brix; that's when you get into trouble if you've added too much.

It seems the Vinmetrica YAN kit (which i have but ran out of time/energy to use ahead of AF) is mostly a (relatively) simple titration, with a lot of reagent prep. The use of formaldehyde and some of the centrifuging/decanting/filtration as recommended in the method does take some setup in terms of capability; is there a simpler way to conduct YAN measurements? i have seen some stuff about spectrophotometry but I think that may exceed my budget at this moment

I bought this kit this year; it seems to work and honestly not too much prep. You do have to be careful with use and disposal of formaldehyde.

How fast generally do the lab results come back for YAN from contract labs like ETS? I would consider sending out the juice to a lab if I could keep the remaining must cold while I wait for results, to delay fermentation initiation; but I'm not sure if my supplier for grapes (Corrados in Clifton NJ) would allow me to store the grapes in the walk in, crush a few, send a sample, wait some days, then pick it up.

I think it depends how close you are to the lab? I live close enough (and in a wine producing region) that we have a courier who picks up daily on request from the winery. We usually get results back same day at this time of year, ie courier picks up sample late morning and we get results by the evening. At most it will be next day. But if, eg you have to ship samples I don't know how that would work. They provide a very good service IMO and if you run their 'juice panel' it saves a lot over just a single assay (eg YAN)

 

[Hazelemere]

Ok so my fall so far, 300lbs Pinot noir , pulled off 5 gallons of juice for rose, put half of those skins back on the remainder.
Fermented red with bm 4x4 used Ferm aid o at hydration, added suggested fermk amount at 1/3 Brix drop, got sulphur smell during ferment, added more Ferm k punched down more - seemed to help but now major hydrogen sulphide smell in carboys .. splashed racked and reduless on its way, questionable if I can save.

Rose fermented with icv-gre - carboyed almost immediately , slight but noticeable hydrogen sulphide smell.

Fast forward several weeks, crushed 100 lbs merlot, fermented lower temp and used Ferm aid o when hydrating yeast as above, added fermk at 1/3 Brix drop. Pressed, racked and ... come on.. hydrogen sulphide, rotten eggs smell again!

Pushing $600 of grapes wasted...

My question is, what is your nutrient addition amounts, and exact addition time?
Also is it possible sulphur sprays too close to harvest a potential source?

Super frustrated and somewhat defeated..
RT

what yeast did you use? Did you use nutrient. If yes which one?

 

[CalicoCellars]

Scott Labs also has a useful yeast nutrition planner.

Thanks! Bookmarked this. Man, these yeast have a better nutrition plan than I do ; I will definitely add this to my winemaking chart book.

I dosed with Kent’s and rough racked the sauv Blanc one more time and used a degassing wand on a drill for 5 mins alternating directions as per previous 2020 batch above; so far, we will see if it attenuates the smell and if not the Reduless will be in tomorrow;

I have a small 1/2 gallon Tempranillo juice I had left refidgerated to have a second settling I can use to practice the YaN method with to see if I get values that make any sense;

 

[Rice_Guy]

You seem to have researched YAN, your questions are good.

seems the Vinmetrica YAN kit (which i have but ran out of time/energy to use ahead of AF) is mostly a (relatively) simple titration, with a lot of reagent prep. The use of formaldehyde and some of the centrifuging/decanting/filtration as recommended in the method does take some setup in terms of capability; is there a simpler way to conduct YAN measurements? i have seen some stuff about spectrophotometry but I think that may exceed my budget at this moment.

Yes spectrophotometry can give you answers in 30 seconds. Yes Vinmetrica is good for home level numbers. I would first of all speed my process up by looking at historical numbers. What I have seen is a supplier usually follows the same pattern for years. Or a grower who fertilizes consistently has better YAN numbers.

I have been running Yeast Nitrogen for a while and am frustrated that there isn't more about what is normal. As a start I contribute this:
View attachment 108203
Deetzil in 2013 had a thread which is a good intro to nitrogen calculations for yeast
https://www.winemakingtalk.com/threads/yeast-nutrients.39655/FermCalc.com is a web based program with lots of choices as yeast varieties -> ie nitrogen demand

Notes:
* a test is about 30 minutes, I have run only a few replicates,
* I do not have a reference lab to compare results with ,, therefore If you run it feedback is appreciated
* this data set was generated with the Vinmetrica reagents and a 0.01 accuracy pH meter
* the test involves three pH based titrations, one of the reagents is formalin (yup that smell when dissecting a pig in biology), it is an easy test to run
* the photo is a formaldehyde titration, the wife kicked me out, , , , as a second option this part is run in the bathroom with exhaust running
* YAN is a ppm quantity, ,, ie mg/liter

* Yes it is nice to mix everything and then sit back. BUT, there is no reason not to get yeast growing > let them consume existing nitrogen in the must > next morning be less rushed and finally add the Fermaid O, > that evening run the formaldehyde titration to see if the guess was right > add a third dosage of nitrogen.
* Yeast nutrition is kind of loosie goosie. With the best information suppliers have they are still learning how things operate. I wouldn’t be surprised if in ten years someone comes up with a vitamin or growth regulator that changes what we understand via Fermcalc.
* Chemical nitrogen is free and reactive. (Ethyl carbamate is a carcinogen), I would try to be accurate in dosing DAP or urea.
* I like your use of Fermaid O and not using urea. I would double dose with organic nitrogen and not worry. ,,, Another way to look at that is using historical numbers we can see YAN numbers vary 100% in a set of buckets. This is assumed organic and the yeast have to work at getting it so they don’t go bonkers like they do with urea.
* Looking as a wine judge white frequently have reductive flavors. Historically we know we should dose whites high with nitrogen/ ignore generic instructions on a YAN product.

@CalicoCellars , good questions.

 

[CalicoCellars]

Added the Reduless ; here we go, will report back if the problem has abated after the 72 hours. Thanks again for the good details; I agree the nutrition plan is better worked out in advance than in haste.

 

[MiBor]

Hey folks; am facing some H2S issues even with Sensy yeast; which is supposed to be a low sulfide yeast. This is in 10 gallons Sauvignon blanc juice. Didn’t get the chance to get YAN measurements but maybe the juice didn’t have additional nutrients

Is there a risk of adding too much yeast nutrient? Is there a threshold? I have heard that the main thing to worry about is potential for microbial spoilage during aging but I am intending the white will only be for 2 years tops and sulfite can also control this, right?

Thanks in advance for any guidance

It looks like you got a lot of good advice from some very experienced winemakers. Reduless works well for H2S removal, but splash-racking white wine is problematic because of oxygen exposure. Good luck and keep us posted.

Among other wines, I've been making Sauvignon Blanc from juice every year for the past 10 years, and I've learned a few things along the way. What I'm about to write won't help you now, but it may come in handy next year if you decide to try your hand again at making SB.

These are the things I've learned to do for a successful SB juice fermentation:

1. Have reliable temperature control. AF temperature can affect the wine in a big way Colder is better (check yeast data sheet)
2. If possible, add pectic enzyme and let it work before fermentation. It will help a lot with clearing the wine when it's done fermenting.
3. If needed, adjust pH and TA before fermentation.
4. Use non H2S producing yeast. This year I used Renaissance Viva and TR-313 in separate containers, then I mixed the wine after AF was done. Good taste and smell and more complexity...
5. Assume 0 YAN and feed with a mix of Fermaid-O and Stimula SB (per Stimula data sheet). This combo is forgiving if you overfeed (also don't add any nutrients after 1/3 sugar depletion)
6. FT Blanc Citrus tannin during and after AF improves the taste (if a citrusy flavor profile is desired). Also, the zest of 1-2 ripe grapefruit added to secondary fermentation can help a wine that lacks aromatics.
7. Once AF is done and you racked off the gross lees, use bentonite to remove stray proteins, then finish clearing with Chitosan/Kieselsol.
8. Cold-stabilize the wine to make sure there is no flocculation happening (SB is usually served cold)
9. Age a minimum of 6 months before bottling, then age in bottle for 2-3 months.
10. Minimize oxygen exposure at all times (rack with vacuum pump, flush carboy neck with argon, etc.)

I realize that some of my suggestions involve somewhat expensive products. Truth be told, I tried many more and the ones I mentioned are only those that made a real difference. The problem with juice buckets is that they are not consistent in quality year-to-year, or even bucket-to-bucket. Without tasting, testing and adjusting the juice from each container individually, making wine from juice buckets is a crapshoot and the steps outlined above attempt to mitigate that reality. Wine kits offer the advantage of more consistent quality and success. Good kits are expensive, but if you can afford them they are totally worth their price. Even low cost kits, with tweaks, can make a better wine than some of the juice buckets I bought in the past.

 

[CalicoCellars]

It looks like you got a lot of good advice from some very experienced winemakers. Reduless works well for H2S removal, but splash-racking white wine is problematic because of oxygen exposure. Good luck and keep us posted.

Among other wines, I've been making Sauvignon Blanc from juice every year for the past 10 years, and I've learned a few things along the way. What I'm about to write won't help you now, but it may come in handy next year if you decide to try your hand again at making SB.

These are the things I've learned to do for a successful SB juice fermentation:

1. Have reliable temperature control. AF temperature can affect the wine in a big way Colder is better (check yeast data sheet)
2. If possible, add pectic enzyme and let it work before fermentation. It will help a lot with clearing the wine when it's done fermenting.
3. If needed, adjust pH and TA before fermentation.
4. Use non H2S producing yeast. This year I used Renaissance Viva and TR-313 in separate containers, then I mixed the wine after AF was done. Good taste and smell and more complexity...
5. Assume 0 YAN and feed with a mix of Fermaid-O and Stimula SB (per Stimula data sheet). This combo is forgiving if you overfeed (also don't add any nutrients after 1/3 sugar depletion)
6. FT Blanc Citrus tannin during and after AF improves the taste (if a citrusy flavor profile is desired). Also, the zest of 1-2 ripe grapefruit added to secondary fermentation can help a wine that lacks aromatics.
7. Once AF is done and you racked off the gross lees, use bentonite to remove stray proteins, then finish clearing with Chitosan/Kieselsol.
8. Cold-stabilize the wine to make sure there is no flocculation happening (SB is usually served cold)
9. Age a minimum of 6 months before bottling, then age in bottle for 2-3 months.
10. Minimize oxygen exposure at all times (rack with vacuum pump, flush carboy neck with argon, etc.)

I realize that some of my suggestions involve somewhat expensive products. Truth be told, I tried many more and the ones I mentioned are only those that made a real difference. The problem with juice buckets is that they are not consistent in quality year-to-year, or even bucket-to-bucket. Without tasting, testing and adjusting the juice from each container individually, making wine from juice buckets is a crapshoot and the steps outlined above attempt to mitigate that reality. Wine kits offer the advantage of more consistent quality and success. Good kits are expensive, but if you can afford them they are totally worth their price. Even low cost kits, with tweaks, can make a better wine than some of the juice buckets I bought in the past.

Thanks for this, this protocol is awesome.

My current hypothesis is that the stainless steel coil I used was imparting too high of a thermal gradient; the point at which the thermocouple was within the bucket may have been reading at the range (55°F - 65°F) but immediately adjacent to the coil it may have been significantly colder (Sub 40°F) and this could have made some yeast dormant and others in the zone above 40 and below 55 to enter a stressed condition and produce the H2S.


^ Coil only axially spans about a few inches of the total bucket height;

I had the glycol temp at -2.5°C or ~27°F to try and minimize the run time with a closer to setpoint temperature; but in the future i think i will accept longer run time on the glycol pump to avoid overchilling; or, I will source a larger stainless steel coil such as this:

https://morewinemaking.com/products/blichmann-cooling-coil-14-42-gal-fermenator.html

I will be getting the Renaissance strains for the next go-around for sure.

You mention secondary fermentation ; do you put your SB through MLF or do you sulfite to prevent unintended MLF?

The SB treated with Reduless seemed to restore the aroma to normal and remove the smells.

Thank you all,

-Mike

 

[MiBor]

Coil only axially spans about a few inches of the total bucket height;

I had the glycol temp at -2.5°C or ~27°F to try and minimize the run time with a closer to setpoint temperature; but in the future i think i will accept longer run time on the glycol pump to avoid overchilling; or, I will source a larger stainless steel coil such as this:

https://morewinemaking.com/products/blichmann-cooling-coil-14-42-gal-fermenator.html

I will be getting the Renaissance strains for the next go-around for sure.

You mention secondary fermentation ; do you put your SB through MLF or do you sulfite to prevent unintended MLF?

The SB treated with Reduless seemed to restore the aroma to normal and remove the smells.

It's a good thing that Reduless worked for your wine's H2S problem. If it hadn't, you would have had to use stronger copper products and copper is toxic, except in very small ammounts. Keep an eye and your nose on that wine though. When I had H2S problems in the past and used Reduless, I had to treat the wine again as hints of it re-appeared two-three months into bulk aging.

I don't put my SB through malolactic, as it's not consistent with the flavor profile I try to achieve. Secondary fermentation refers to the second part (anaerobic) of AF, when yeast doesn't need oxygen anymore and it is less aggressive, therefore allowing add-on ingredients to impart flavor. Most additions at the beginning of fermentation lose their delicate flavors due to yeast voracity and oxydation.

Your temperature control setup with the stainless coil is ok but you need to add an agitator that constantly moves the wine, in order for it to be effective. It can be a stirrer paddle with a motor (on the lid of the fermenter) or a small pump on a timer, however you want to go about it. The purpose of it is to prevent the formation of very cold (or hot) zones in the proximity of the heat exchanger. Professional tanks are jacketed, meaning the heat exchanger is built into the wall of the tank, and the need for agitation is greatly reduced that way. For home use, the coil in the tank approach works fine, provided there is some way to move the wine around to even out temperature throughout the volume of liquid.

 

[CalicoCellars]

Thank you for the additional vote of confidence on the setup. I guess the key to agitation is to not break the surface tension and to be gently stirring; stir gently enough not to take on oxygen and oxygenation, and stir enough to get bulk fluid movement in order to properly eliminate the temperature gradient. I’ll have to do some trials with temp probes at different locations (like a smalltemperature mapping study. One at top center of liquid, one probe in the dead center of the tank, one on the bottom center of bucket, and one on the coil directly) I imagine a low speed dc motor with a speed controller and or Arduino timer would do the job.

 

[Nic_B90]

Are you smelling the H2S in the Rose your making? I think it can be saved. First step for future reference…before any fermentation for whites and Roses is to settle the freshly crushed juice for 24 hours, and then rack the clear juice off the sediment that has fallen to the bottom of the fermenter you’re using. The sediment can create off aromas like H2S if not racked off before fermentation. This is what commercial wineries do. When hydrating the yeast I would suggest GO-Ferm yeast nutrient rather than fermaid O. For your current situation I would use a product from Scott laboratories online called REDULESS that can mitigate the H2S. I’ve used this product on 2,000 gallons years back and it worked well. Let me know if you have any more questions. Been there done that!! Haha

 

[verdot]

DAP can (and should) be added to Fermaid K if YAN is below 125 mg N/L. I’ve had H2S issues in the past just using Fermaid K. So far no issues with Fermaid O, however.

If Reduless is not effective at first, you can rack and add an additional dose. Do a bench trial if possible. The reaction is quick and your nose should tell you if you’re at threshold. I did this for a white wine that still had H2S after the first dose. The second addition took care of it.