What your doing sounds good to me.
potatoes and the slurry will compost quickly without robbing the soil, but will add to it.
The way I understand it, the longer a product takes to decompose, the more nitrogen it uses.
I use everything except:
1. Egg Whites.
2. Egg Yolks.
3. Beef/Lamb/Pig/Chicken, meat, fat, skin or bones.
4. Papers of anykind that are heavy with chemicals.
I do use:
1. All Kitchen trimmings of vegies.
2. Paper towels that are not soiled with meat products such as fat and blood.
3. Hair.
4. All yard waste,
weeds, fading blossoms, lawn clippings, etc.