I just use a dessertspoon
One level dessertspoon. They tend to be about the same size - there may be some variation, but a level dessertspoon would be fine - not too much, not too little. ie the spoons you eat cereal and pudding with, not the larger tablespoons. Spoons do vary in size in different countries too. If you have a set of measuring spoons for baking if tends to say how many mls for a teaspoon. A teaspoon tends to be 5mls and that is equivalent to 5 grammes. A tablespoon is 15ml (Amercian measurements).
I tend to think it's better to give the same amount each day, once a day, but not refill it if it's empty, as Elusive says. They do hoard most of it but then they eat from their hoards. The hoard makes them feel secure, as they are hard wired to think there may be a food shortage.
It may seem a waste of food, but in the run of things, hamster food is not that expensive, and a bag lasts a long time, so if it keeps them happy and feeling secure, it's a small cost perhaps
How often do you clean the hamster out? Cleaning them out a lot can make them anxious about their hoards being "stolen" so that can make them start peeing on the hoard to deter thieves! That can be a bit of a vicious circle, as then you have to remove the hoard (or some of it) if it's pee'd on so they pee on it again because it's been "stolen"!
If it is pee'd on then you do need to remove it, but it's best to try and leave some of the old hoard behind, that isn't damp, and also add a dessertspoonful of new food to replace it. To help stop them peeing on it out of habit, you could add the new food slightly to one side of where the hoard is, in a new location. And it should settle down.
If you mainly spot clean, then it won't cause stress from overcleaning. I leave the hoard and nest alone when spot cleaning, but when it's time to do a more major "half clean" I then prune the hoard from underneath, removing the bottom half, which is the older hoard, but leaving some behind.
Some of all this depends on what size cage you have and how much depth of bedding you have - the more bedding there is, the less you need to do a cleanout. I have a robo and I when it's time to do a clean (and I leave it a few months, with spot cleaning in between) I do one half of the cage - eg the left half or right half so the other half is still smelling familiar. Then a couple of weeks later, I'll do the other half of the cage.
What cage do you have? If you want to post a photo of the set up, we might be able to suggest some more tips to get the behaviours back to normal
