Water and dry food expansion

I am in the middle of testing 2 different dry food for expansion with water. Started 1 hour ago, with equal amount of dry iams food and dry premium edge food. One is a good quality (premium) and the other one is (iams) corn and filler cheap food.

I have filled to small glasses of dry food in each same glass. Then poured into bigger 2 glasses of same size, and added water until it just starts to float to the same marked height on the glass (used scoth tape and a non permanent marker to be a bit more accurate.

So far one hour has gone by.

Both cheap food and quality food have expanded about 10-15% or about 3/4 of an inch expansion in 1 hour. The quality food expanded about 1.5 cm and the cheap one about 2 cm for metric users. Will monitor for next hour to see if further expansion evolves. Unless the dog eats way more then it should i don't believe it should be a factor in a dangerous expansion if they eat normal amounts of food and water.

Now on the chemistry side of it, I INVITE ANYONE QUALIFIED to test the possible reactions between the food you give your dogs and other food or treats you also gives your dogs. Maybe talk to a animal nutritionist like the ones that work for a zoo.

If i wanted to feed my dogs and not spend more then 25$ /week, i can expect they will have some kind of problem down the road. Hey, even my best friend, was told that giving pumpkin paste with the dry food was good for his dog to not be so hungry, and good for his coat. I am sorry but i don't believe stuff people say just like that, and perhap risk the health of my non-talking dogs. It is ok to be foolish and dumb when your not even 25 years old yet, but after that i mean, we are supposed to get wise, the grey hair does not guarantee that LOL.