I have received many emails about how to find the ideal weight of a  fly or spey reel to balance out a salmon or spey rod. Since the thickness of the rod taper and where you grip your cork is unique to each individual fly fisherman, the answer to this question is difficult for me to decide, but can be determined by the spey fisherman with ease. This will also take the guess work out of purchasing spey equipment. Its the old adage of "What came first, the chicken or the egg?". In this circumstance, I believe it is the spey rod. It is important when deciding on the proper rod to consider the size of the river that you will fish most often and the size of the fish that are in the river. The second purchase should be the reel, which is where this little exercise will be invaluable. When choosing your reel, you will need to determine the line and backing capacity needs. The third decision should be the proper weight to balance your rod in hand. This, in my opinion, is the most important step.

Having a balanced spey rod will save on fatigue in two ways. First, you won't have to grip the cork so tightly to lift the tip off the water all day long. Second, in your forward spey casting stroke, a heavy reel will help bend and load your rod without having to you having to exert extra energy. When spey casting, unlike double hauling, your arm is only in the air for seconds. The rest of the time, your arm is in the resting position waiting for the pull. Your upper hand is the "fulcrum" or "pivot point" and your bottom hand is the "counterweight", if you will. By having a heavy bottom hand, the rod will flex and shoot line by using gravity instead of using muscle strength. Also, when you have to grip something so tightly in the resting position, you decrease blood flow. By relaxing your arm and letting your rod balance naturally, you will be able to loosen your grip, increase your blood flow and fish all day without having a heart attack - that comes with the grab!

I will share a simple two step process for which you will need only a few simple supplies before you get started. These include only your spey rod, a plastic sandwich bag, some tape and a handful of weights( PENNIES, ROCKS, MARBLES, CAT FISH WEIGHTS).

Tape the plastic bag to your spey reel seat then add weights until the rod lays across 4 fingers in the resting position. At this point, count or weigh the bag contents, and then you know what your reel should weigh - and I mean really know - not someone else's opinion as to what they guess might be right. Since every one holds their rod in a different spot on the cork, the correct balancing weight will vary from person to person.

It is also worth noting backing adds weight to your reel. I pulled out the grain scale and weighted some dacron backing and here is the simple formula I came up with. 
#30 Pound dacron = 0.01 OZ per 1 YARD
#20 Pound dacron = 0.01 OZ per 2.5 YARDS
This makes the math very easy.
100 yards of # 30 backing weighs 1 OZ . 
125 yards of # 20 backing weighs 1/2 OZ.

Now, armed with this info, looking for a reel that matches the rod in your hand is easier. With the purchase of any of my reels I can add or subtract weight to your build before I send it to you, so your new reel will be customized uniquely for you, to achieve perfect rod / reel symmetry - just plan to be surprised on how much weight it really does take to achieve this !