Looking back not sure why I decided on these proportions as it does not match the video. Also, when I first tried making it mid-April our house temperature was not optimum for yeast growth (<20C) so it took a lot longer to get it active and to double in volume. Temperature is really critical for this 'pet' yeast.
Day 1: 5g rye flour + 5g water
Day 2: 5g rye flour + 5g water
Day 3: 5g rye flour + 5g water
Day 4: 10g rye flour + 10g bread flour + 20g water
Day 5: 15g rye flour + 15g bread flour + 30g water
Day 6: 15g rye flour + 15g bread flour + 30g water
Day 7: Decide what you plan to make and prepare what you need and have enough to keep a stock. Take 40g of starter + 20g rye flour + 20g bread flour+ 40g water ( it should double in volume prior to use. 110g for bread and leftover is fed and kept as a stock)
discard the leftover or find sourdough discard recipes and use it.
Caring for 'pet' starter
If you want to keep starter at room temperature then you will need to feed it every 24 hrs. Take starter weight and feed it with equal amount of flour and water. example: 40g starter, add 40g flour and 40g water.
Keeping in the fridge
Start with at least 60g starter and add 60g flour and 60g water mix throughly and cover with saran wrap with a gap to allow air to enter. Refrigerate it. By doing so, you are slowing down the yeast activity. At day 7 feed the yeast.
Reviving yeast from fridge or feeding at day 7
Typically there is a hard crust on top of the yeast when it is refrigerated. Peel off the hard crust and stir the yeast mixture and let it sit at room temperature (22C) for at least 8-9 hours.
I would take it out at 10pm then at 7am in the morning feed it then put in the fridge or leave it at room temperature and use it for baking at 4pm.
7am: 80g starter + 40g bread flour, 40g rye flour, 80g water (green ruber band marks the initial level)
4pm: yeast mixture has more than doubled in volume, stir it down and use in recipe.
used 220g to make bread and had 20g leftover.
In a bowl 20g starter + 10g bread flour + 10g rye flour+ 20g water (picture below) this will be the new stock
If you want to build up the quantity faster to use for next baking feed it every 12 hrs. Take all the starter and feed it equal amount of flour and water.