Filtering can render wine instantly clear. Filtration can remove yeast, bacteria, and grape debris from the wine, making it more stable. Stable wines are less likely to change their appearance or taste with time. By removing yeast or bacteria that could referment the sugars, the amount of SO2 and other chemical preservatives can be reduced.
Filtering works by removing small particles from wine. If your wine is young (less than two months old) or very cloudy, a filter will clog too quickly to clear any of the wine. The large particles in a young or cloudy wine block the filter pads, causing the pressure inside the filter plates to rise. This in turn causes the wine to spray out the sides of the filter and puts stress on the pump and hoses.
You can only filter a wine that is almost clear already. This cannot be overstressed.
Before you use a filter on your wine it should have been racked at least twice and should have also been fined. Anything less and you could wind up simply clogging an expensive set of filter pads and setting yourself up to spray the walls with wine. Filtering is literally the last thing you should do to your wine, just before you bottle it. If you are putting the wine in bulk storage and not bottling it, you shouldn't filter. Just rack the wine into clean containers and store it until bottling time.
Also, you need to make sure that your wine is properly sulphited before it goes through the filter. The pump that the filter uses can introduce oxygen into the wine. Having the correct level of sulphite will prevent this oxygen from damaging the flavour and colour of the wine. You should have 50 parts per million (PPM) of potassium metabisulphite before filtering. This amounts to 3 grams per 23 litres (½ tsp. per 5 gal.).
Which pads to use
Choosing the right pads will ensure that you get the right kind of filtration for your wine. The wrong kind of pads will leave your wine cloudy or clog too quickly.
Number 1 pads remove large particles but you won't notice a significant change in your wine. They could be used on young wines at racking to remove heavy sediment but this isn't a good idea. Any particles that are large enough to be caught by the pads are likely to foul the pump, blocking it and making an overhaul necessary. For removing particles that size, it's best to wait and rack the wine as it clears itself or to use a fining agent.
Number 2 pads are the workhorse of the Buon Vino filter. They remove haze-causing particles from red and white wine without stripping too much colour and flavour. After a wine has been put through these it will show a significant change in clarity and brightness. These pads are the ones you should be using for most of your wines, and the only ones to use on your red wine. Depending on the clarity of the wine being filtered, they will do 46 litres (10 gal.) or even 92 litres (20 gal.). You must use these pads first if you intend to use the number 3 pads.
Number 3 pads are for finer filtering. One pass through the pads will remove 80% of the yeast cells in the wine and two passes will reduce the yeast population to the point where further fermentation is unlikely. They will leave the wine as clear and bright as water. Used improperly, however, they can also leave the wine tasting much like water. These pads are so fine that they are capable of removing colour and flavour compounds from the wine. If you are starting with a delicately flavoured wine it can wind up almost under-flavoured, stripped of its character. And red wine can be stripped pink. Number 3 pads are used mainly on wines that contain residual sugar. With fine filtration to remove the yeast cells, wine makers can reduce the amount of chemicals needed to stabilize the sweet wine.
Setting up the Buon Vino for filtering
1. Sanitize all the surfaces that will come in contact with your wine. Remove the filter plates from the machine and dip them in a sulphite solution (or even better, fill a trigger spray bottle with your sulphite solution and use it to spray everything). Run sulphite solution through the hoses and the pump motor. Then rinse the sulphites off and out of everything. Return the plates to the machine, making sure the semicircular tabs are on top and aligned with each other.
2. Prepare your pads by making up the following solution in a shallow sanitized pan. To one litre of cold water add one gram (1/8 tsp.) of potassium metabisulphite and 3.5 g (one tsp.) of citric acid. If you don't have citric acid use two teaspoons of lemon juice. Dip each pad in this solution and hold it under for three seconds to allow it to saturate. This will remove the 'cardboard' taste from the pads and sanitize them. It's important not to use too much sulphite--it could get transferred into the wine.
3. Put the pads into the machine. The rough, uneven side of the pads faces the motor. The holes in the pads should line up with the holes in the plates.
4. Once the pads are in and lined up you can gently tighten the threaded screw in the centre of the plate. This screw should only be hand-tight. If you use a wrench on it you will accomplish two things: One, you'll damage the plate-frame unit. Two, you'll void your warranty. Remember, it will leak a small amount anyway, so over-tightening it won't help.
5. Make sure all of the hoses are in place and tight. The intake hose attaches to the right side of the machine as it faces away from you. The transfer hose goes from the left hand side of the motor into the lower left corner of the plate assembly. The outlet hose attaches to the top right hand side of the plate assembly.
6. The next step is to put the legs under the plate assembly into a sanitized shallow pan or bowl large enough to extend under the pads and plates. This will catch the wine that leaks which you can save and re-filter. After your drip pan is in place, run 23 litres (5 gal.) of cold water through the machine. This will wash any cardboard dust off the pads and remove the remaining traces of sulphite and citric acid. Check the machine for leaks, and empty the drip pan. Your Buon Vino is now ready to use.
Filtering your wine
1. Dip the intake tube into the wine to be filtered. If there is any sediment in the container you should attach a ½-inch syphon rod (with an orange syphon tip) to the end of the intake hose. This will prevent sediment from getting into the pads and clogging them prematurely.
2. The wine being filtered should be higher than your Buon Vino so the wine can flow downhill. The filter should be higher than the destination container, again, so the wine can flow downhill. This will allow you to take advantage of the natural syphoning that happens when liquid flows downhill, which will reduce the amount of work that the pump motor has to do.
3. The first ½ litre of liquid that comes out of the filter will be the last of the fresh water you used to rinse the pads. Keep a small container handy to catch and discard this. When the wine starts to come out, quickly change the outlet hose to your receiving vessel.
4. If you are filtering more than one kind of wine you don't necessarily have to change the pads for each batch. If the pressure gauge shows that the pads aren't yet plugged (see below) you can continue to filter your next batch of wine on the same set of pads. A good rule of thumb for consecutive filtering is this: filter light whites first, then heavier whites, then light reds, then heavy reds.
For SuperJet and 10 Plate Filter
Reading the Pressure Gauge
The pressure gauge screwed into the plate assembly is there to tell you when the pads have become too clogged to filter any more wine. When you are running water through the filter, the gauge will usually not show any pressure. When you are using the number one or number two pads, the pressure will gradually rise from one or 2 p.s.i. to 18-20 p.s.i.. When it reaches this level, the pads cannot pass any more wine and need to be changed. When you are using number three pads you have to watch the gauge carefully. Immediately after wine begins to flow out of the filter, make a note of the pressure reading on the gauge. It should read between 5 and 10 p.s.i. As wine passes through the pads, the gauge reading will rise. When it goes 10 p.s.i. past the original reading it is time to change the pads. (i.e., Starting pressure of 6 p.s.i. rises to 16 p.s.i.) It's important to watch the gauge carefully. If the pressure rises too high, the wine can burst through the pads and go through unfiltered. Excessive back pressure can also damage the pump motor.