Please realize that the amount of ballast needed to bring a plane into balance is not relevant as long as the model's gross weight is not out of line. The Great Planes Slow Poke has a very short nose. That means that it WILL take quite a bit of weight to balance it. OK, you do what's necessary. The .25-size Slow Poke should max out at about 3.5 pounds, and the .40-size at 6.5 pounds. Stay within those parameters and you'll be OK.

A "correctly-designed" airframe may or may not need a certain amount of weight to balance. Many people have the mistaken idea that a "correctly-designed" model should need no weight or very little. That's not so. It all depends upon what the model is designed to do. I had a large glider that required several POUNDS of weight in the nose to get it to balance properly. The gross weight of the glider was below the designed gross weight, so I had no concerns at all about adding weight to balance it. The Slow Poke's design is intended to be a fun model with a very large wing...it's a floater-type, and the intended "look" of the airplane gave it a rather short nose. It's not at all surprising that it may need more weight than some people may think it "should" have. Just balance it where suggested and be done with it. Again, as long as it's within the design parameters for total all-up weight, what you have to add is not relevant.