Hi - some observations from over the years ...
Back in early 90's I grew koi to 70cm in 4 years in a pond of 18,000 litres and only 80cm depth.
I used Hikari Staple to achieve this. I recorded everything then wrote an article on the high cost of this exercise. This was the birth of Shogun - without going into gory details.
I also had the problem of different size koi but could only afford one size pellet. So I dampened the large pellets. The little ones and the large ones could now ingest the same pellets. The very small koi could easily bite of pieces of the damp pellets.
I am absolutely convinced to this day this was part of secret of the growth I achieved. Because the pellets were damp the koi ate more. Wheter the damp pellets replicated a natural way fod digestio I do not know. Dry pellets are taken in by koi who swim away to chew them. By the time they return the feeding is usually over. So tough the fish does not get enough.
When you think about it damp pellets make sense. Everything a koi eats is damp or wet because it is in the water - the exception is the dry pellets we feed. Even blood worms, earth worms etc are damp/wet. The only reason we feed dry pellets is shelf life. Koi food has to be dried after manufacture to below 10% moisture or the yeasts will active with disastrous results.
If koi food becomes damp it will become mouldy over time. These moulds can produce some deadly toxins. So always make sure you keep the koi pellets dry. Never place on a concrete garage floor for example. You will be surprised at the amount of moisture that comes through the concrete.
If you decide to feed your collection on damp pellets - this is the way I have been doing it for many years - take the amount of pellets you are going to feed the koi - say cup or mug full. Add warm water from the tap. Leave the water and pellets in the mug for 5 - 10 seconds. Throw the water off. Now place the pellets in a bowl - something like a soup bowl. Leave the pellets to stand for about 15 minutes. The moisture is absorbed into the pellets, they become soft but retain their shape. Now feed to the collection. I usually just throw the bowl onto the surface of the pond and let the collection get on with it.
The important thing to remember is never leave the pellets floating in the pond or never leave the water in the mug. After time the water soluble vitamins will leach out rendering the pellets close to useless.
Only dampen the pellets you are going to feed that day or at that feed. Do not keep overnight. In this way you can feed all size koi one size pellet - large pellets.
A dealer did this a number of years ago. She had a soup bowl full of pellets. Every half hour or so she would spray the pellets with water using one of these hand held sprays. Then she left the pellets for 10 or so minutes. As she walked around the sales tanks she fed the top layer of damp pellets. Then later she would spray the pellets again and repeat the process.Sshe fed large pellets to small koi using this process.
Hope this helps,
Regards,
Chris