I have been doing cellar work new to the industry for 3 months and wondered what peoples thoughts are on adding water to their brights when you run short after filtering. The filtering goes perfect but sometimes as much as 25-50 gallons is short from the bright. Never more than 2 barrels. Recently I found that when this happens we add water to the bright to make up for it. Is this a normal occurance in the industry? I would expect if not I won't get many responses. If it is, what is the max ratio that can be used to no break down the original beer style/taste.
I can't speak for anyone other than our brewery. I have never made up volume with water anywhere in the brewing process beyond lautering. I think anything more than a couple of percent would start to alter the flavor and body, not to mention greatly increasae the risks of contamination and oxidation (depending on how the water was prepared).
What he said. Just say no to adding water then. If you're consistently getting a barrel or two less than you want, put more water (and grain and hops) in the brew to begin with!
I'm not sure what the licensing laws state over in the US (I assume you are in the US), but if you say you are selling a 5% ABV beer, and you you brew it to achieve 5% ABV in MV, but can then only achieve say 4.5 % in serving tank, then you are, first of all, cheating the customer, both in alcohol and flavour terms, but I wager you are also not within the licensing regs.
The easiest way to resolve this, as previously said, is to brew at higher gravity to achieve say 5.5% ABV so that after the inevitable dilution of filtration you actually achieve your target 5% in serving tank.
If you have a horizontal leaf filter, you should be able to blow the filter tank out with CO2 once you have precoated it. You then slowly fill it again (from the bottom of course), recirculate for a few minutes to re-establish the filter bed, and then start filtering to your bright tank. At the end of the filter run, depending on the design of your filter, you may be able to blow the bulk of the beer out of the filter with CO2 top pressure, through the bottom filter disc. You may well still need to brew at high gravity to make up for dilution incurred elsewhere in the system.
If you have a plate and frame filter, the only realistic way for a small brewery (and indeed a large brewery, though they have more leeway due to the large filter run lengths) is to brew at higher gravity (for higher ABV) to allow for the dilution.
I assume you are carefully purging all water out of the mains between MV and filter and filter and bright tank. Make sure you are running your filter at the design flow rate. If you are running it slower, then you will get excessive mixing, particularly in the filter. This also applies to the pipes, where you need to aim for between 1.5 and 2.0 metrres second (say 5 to 7 ft / second)
Make sure your filter powder slurry is not too dilute - a 10% w/w slurry is typically used.