Hydrolux ppm will continuously rise over time. Because of the durability of the membrane and the titanium used it takes a bit longer to break in but with consistent use this will not be a factor.
Also if you are using a liquid reagent for testing we have discovered that some reagents are actually not diluted and formulated properly. We make a point to acquire the reagent made in Japan and to check for this. In most cases it is the fact that Hydrogen escapes so fast testers cannot account for the amount of actual hydrogen in the water because it is releasing too fast. Especially electronic testers as this is not the way hydrogen concentration is accurately tested in the laboratory since they are unreliable.
There is a method that a boiled egg is placed over the mouth of the the testing cup right after generation to prevent the hydrogen from escaping and a needle with reagent is place into the egg and dropped in to the water. Again Hydrolux ppm will keep going higher and it will out perform any unit on the market because we use higher quality parts, a pressurized cap to force the hydrogen back into the water, double walled glass, and a dupont/chemors membrane.