For what it is worth, here is my approach..
Prevention - Use The appropriate amount of yeast neutriant in stages. I normally add in 3 stages to give the yeast a steady amount of neutriant during the fermentation life cycle. I add half up front, during the lag phase where growth is the main focus. I then add the remaining half in two stages later on.
Low Impact Treatment-
1) Splash Rack immediately. The most likely cause of your h2s is (as deezil has said) stressed yeast. Getting any residual lees out of the equation goes a long way to prevent the problem from getting worse.
With H2S, an amazingly small amount will knock you on your back. just 2ppm will seem shocking to you. Since we are talking about such a small amount, many times a splash racking will be enough to cure the issue.
2) Add k-meta to about 35 - 50ppm. This will go a long way in "killing/stunning" any remaining suspended active yeast, thus helps to prevent the problem from getting worse.
** after you try 1 and 2 above, give the wine about a week and check it again. If the issue has not been corrected, it is time for more hard line cures..
Hard line cures (addition of copper):
Copper will bond to H2S to form an insoluable compound that will settle out of the wine. The question here is one of delivery. There are a number of methods..
1) Bring wine into contact with copper metal (wire, pipes, or even copper sheeting. Some use copper pipes, but my recomendation is to get a piece of copper flashing. This will give you much more surface area than wire and also can be scoured with a scotch-brite pad (unlike pipes). Scouring the copper is needed as this will remove any tarnish or oxidation, thus improving the amount of contact that the wine has. Simply bend the flashing into a funnel shape and use as a funnel when you rack.
This method, although easy and mostly effective, is not the best choice. The amount of copper you use needs to be tightly controlled and this method has no way to regulate itself.
2) perform a bench trial using copper sulfate. This is far more effective that using copper metal. You do need to keep in mind most problems are caused by very minute amounts of H2S. Bench trials are a must since copper sulfate is not exactly a healthy additive.
It is simple, set up 2 samples of 100ml each of wine. One you leave alone as a control. Using a 3 ml syringe, add .25 ml at a time. For each addition, swirl the sample for 30 seconds and then sniff. Keep adding until you feel you have the problem licked. Take the total volume of copper sulfate used, and scale to the total volume you need to treat.
3) Reduless - This is a product that is actually dead yeast that has been infused with copper. I have used this product in the past and must say it works like a charm. You add an appropriate amount, stir, wait 2 days, then rack. This product has the advantage of delivering a measured amount of copper without the health concerns f copper sulfate.
Hope the above helps.
Dragon blood being a very light wine on fruit doesnt have much in the way of nutrients for the yeast as Deezil says, if the gravity is not to low you can add some balanced nutrient like fermaid to help the yeast after you splash it. If you put the racking cane up high on the neck of the recieveing carboy you can get it to spread out in a film and that helps expel some of the gasses. I dont think going to extremes is worth it for a DB, if you add to much copper sulfate you can poison yourself, and if you stir it with a copper pipe you have to know when to stop or you might get a metallic taste. Pasteur Red is a much better yeast to use in my opinion, much less prone to nasty farts. WVMJ
