Hi all,
You just need to keep on feeding them, make sure you top it up as soon as the food has gone (I have the Grindals by the aquarium, and look at them morning and evening when I take a small wipe from each tub, and put it in the tank for the fish). The White-worms are in a cupboard in a cooler room.
The Grindal cultures grow quicker than the Whiteworms, and after about 10 days you should have a thick mass of worms under the cover (I've only ever used glass or plastic). The White worms took about a month to get going but now they are a really thick layer.
Both worm cultures should look like this when you start feeding them to the fish:
You should be able to keep them at about that density for several months, after that the culture will go sour, productivity will drop off, and need re-starting. If you find that the number of worms dwindles as you feed them, start another culture until you have enough cultures so that feeding doesn't really case them to dwindle in number. If you start harvesting too early the culture will never really get going and won't be anything like as productive. If I'm away for a few days I feed them with "rolled oats" rather than "instant porridge oats" as these take longer to be eaten. I tried feeding the cultures with dry cat food ("Go-Cat"), but that ended up as a horrible smelly mess, so I've stuck to "Ready Brek"/ rolled oats ever since.
You can prolong the culture life by adding some Red worms (
Lumbricus rubella), but you will need to thin these out fairly regularly as they tend to take over otherwise. I also have mixed Red/Grindal/Microworm cultures, and although these need a little bit more management they are still pretty low maintenance.
cheers Darrel