A: In a previous column (1), I mentioned some small, magnetically coupled centrifugal pumps that I feel are suitable for use in general home brewing. The trouble with these pumps is that they have a temperature limit of 200° F (93° C). They are fine for pumping cleaning solutions, cold wort, and hot wort from the lauter tun, but not for boiling-hot wort. And that, as I understand it, is precisely what you need -- you want to pump hot wort from the kettle to the wort cooler. What you need is a pump with a metal body (the centrifugal pumps mentioned earlier have plastic bodies, hence the heat limitation).

Fortunately, a home brewer who stopped into my brewpub recently happened to tell me about a small stainless steel centrifugal pump he uses called the Grundfos, model number UP15-18SU (catalog no. 2P311). It is sold by W.W. Grainger (Chicago, Illinois). This pump is rated to 230° F (110° C) and should be capable of doing the job for you. Be warned that it is not a sanitary pump and therefore should not be used to pump cooled wort or beer. It should do fine for pumping hot wort from the grant to the kettle, or from the kettle to the heat exchanger, as well as for moving hot or cold water and cleaning solutions.

The biggest limitation of centrifugal pumps is that they must be placed below the supply tank. Usually this is no problem because the kettle stands on a burner anyway. Another limitation is that as the "head" -- the resistance on the pump imposed by piping, valves, and lift, expressed in feet -- increases, the maximum flow rate decreases. When the head reaches a certain point, the pump simply cannot move liquid. Small centrifugal pumps have very low head limitations. The maximum head this Grundfos pump can take is about 7 feet. With 7 feet of head, the flow rate will be a bit over 1 gallon/minute. If this limitation poses a problem, you might consider redeploying your equipment in some way. For example, you might put your kettle on the middle level of your three-tier stand, with the hot liquor on top and the mash/ lauter tun on the lowest level. Then you could pump your wort from the grant up to the kettle, and pump from the kettle to the heat exchanger as well.

You also need to consider the limitations of the motor. One of the attractive features of one of the plastic pumps is that they come with a TEFC (totally enclosed fan-cooled) motor, which is highly water resistant. The stainless steel Grundfos pump is only available with a conventional open frame motor, so you would have to be careful with it. I would not recommend putting it on the floor -- sooner or later you will spill something on it and fry the motor windings.

If you decide to buy the Grundfos pump, you will also need the coupling kit W.W. Grainger sells; it consists of two unions that enable you to hook the pump up to regular pipe fittings.

A: In a word, the answer to your first question is "yes." When you work with a mash/lauter tun, you must include the foundation water (the water required to cover the false bottom) in the volume calculated for the mash. For example, my mash/lauter tun at Blackstone Restaurant and Brewery requires 1 bbl of water (31 gallons) to cover the plates. So when I calculate the volume of mash water for a new recipe, I first compute the strike water volume (1 bbl for every 100 lb of grain, which is 1.24 qts/lb), then add 1 bbl for foundation water. Calculating the mash water volume in this way should ensure a consistent mash thickness, regardless of the amount of grain being used. Of course, the grist composition also influences water requirements. Barley flakes, for example, tend to swell up in hot water, and you may have to use extra water to compensate for this factor. But the basic calculation at least gives you a starting point from which to make adjustments.

The answer to your second question is also "yes." There is no question that a large space below the false bottom means more first wort will be run off. But on the other hand, you will have to begin the sparge operation with more mash water in the mash/lauter tun, and when it ends the same will be true. So your total water use will be higher. The unfortunate part of all this is that you will not be able to rinse the grains as thoroughly, even though you are using the same volume of sparge water. This means lower extract. If that bothers you, I suggest substituting a slotted copper tube collector for your false bottom. This will give you a much smaller dead space at the bottom of the vessel. Alternatively, you could double your batch size; a 15.5-gallon beer keg mash tun is plenty big enough for making 10 gallons of beer at a time. This would cut your dead space down to a more reasonable proportion of your total mash volume and raise your efficiency considerably.

A: It seems unlikely that your 40% hop utilization figure is valid; in my experiences, most home brewers get 20-25%. You stated that you determined your bitterness levels by taste comparisons. What commercial beers did you use as references? Most imports and many microbrews have serious oxidation problems, which means a significant loss of bitterness in the bottle. The best beers to use for taste comparisons are the lagers made by the major American breweries. Those beers are almost always fresh. Of course, you would have to brew a light-bodied beer with only about 12-15 IBUs for the comparison to work.

Hop utilization in the kettle decreases as the wort pH decreases. Considering your procedures (pH adjustment and water adjustment as well as decoction mashing), I see nothing that would account for abnormally high bitterness.

Question: Is the bitterness smooth, or do the beers have a rough, biting finish? If the bitterness is rough, you may have a calibration problem with your pH meter -- in other words, your wort might not be as low in pH as you think.

I think you can be confident in the alpha-acid numbers of your hops, assuming that your homebrew supplier is knowledgeable and buys hops from a reputable wholesaler. In any case, the 4.5% you quote sounds reasonable; I have never seen Liberty hops with an alpha-acid rating over 5%. And, as you probably know, mistreatment of hops during shipping and storage will lower their bittering value; it never raises it. If you suspect that you have gotten some mislabeled hops, try a different supplier. But I doubt this is your problem, unless your 40% utilization is a recent phenomenon that coincides with your purchase of a fresh lot of hops.