I replace 50% of my compost in my tubs every year. I remove the top half then mix fresh compost in with the compost left and also add a good handfull of Gromore.

The 50% that i remove goes into the compost

I do the same but scatter the removed compost on heavy clay parts of the garden.

I do about the same as Badfish.A waste of good compost if they are mostly summer bedding plants..it isn't necessary for one season..my old compost is mainly thrown on the borders..the rest in the Compost bin..

Yes you can just mix in some new fertiliser or slow release granules, but its as well to tip it all out first and check for pests in the soil. Top soil on its own isn't always a good idea in containers as it compacts more easily than potting compost and can go solid and hard if its gets too dry. It can also be rather heavy in hanging baskets. If you want to use it mix it half and half with potting compost.

I change old for new every year in small pots though.

My discarded compost goes on the borders as above, it does help to improve the texture.

An article in gardening 'Which' indicated that compost in pots can be used for about 3 seasons with only the addition of slow release feed granules in each spring.
Which also found that there is no need to puts crocks into the base of containers for drainage. It made no difference. I put stones in large containers and cover with fleece before adding the compost more to increase the stability of the pot in the wind. Should I post this as a separate thread?

You don't need to post as a separate thread,Barbara..it's fine as it is..I add a few crocks to my large pots,but fill them at least a third with broken up polystyrene ,saved from packaging,or plug plant containers,as it's a waste of compost for most bedding plants..they don't need that depth..

There's only one cautionary note for reusing old potting compost - don't reuse if the plants you grew in it last year showed any disease, particularly fungal infections like rust. Some plant infections leave spores in the soil which will reinfect new plants placed within. Equally, infestations such as vine weevil, where it's probably wiser to dump the compost and use new in a cleaned pot.

Otherwise, its okay to keep the same compost, just turn it over, removing any weeds and moss, stir in a handful or so of Growmore granules and replant.

Welcome to the Gerbil Magic Mix Site. I bought 2 Gerbils who live in my old fish tank, keep their litter tidy.
They have to have something to chew then they dont fight. Love different shapes, such as egg boxes.
I get thick cardboard from a shop wheelie bin, split it
and make into rolls with old wool.
They love these.
They run in and out of them, pull them around the tank,
then set to and chew them up into minute pieces.
Once a week I renew the litter, which they get very excited about.
The old litter I add to old compost, add Blood Fish and Bone, plus Horticultural Grit Sand, give it a good stir, which makes new compost without using peat or humping heavy bags about.
I am so glad I got Bubble and Squeak. They cost very little to keep. The compressed wood shavings £1 a week. They like to sit in a 7" soup plate on a tablespoon of Gerbil Mix food, once daily. I dont handle them, as their teeth are very sharp. Also keep 2 heavy books on the tank lid, as Squeak enjoys climbing on the water syphon jumping up and banging her head on the lid, trying to open it to get out. She cant figure out why this is not successful !
Great fun. Recommend. Any queries send me p.m.

Its really good to hear how pleased you are with your new pets Diane - You didn't expect them to be compost makers as well as pet did you?

No. I learned about renewing old potting soil from a library book, which I quoted in a previous post. It is also important because it is Peat Free.

I dont have to drag heavy bags of compost from the car any more. The Gerbil crushed wood shavings are easy to carry, the Blood Fish and Bone are complete plant nutrients, the Horticultural grit Sand included for roots to grip on. I have learned to find the thick cardboard in a local shop wheelie bin. Split it and tie into rolls which they love running through, then set to and bite it into tiny pieces.
Pick it up and leave on the back seat of my car until I need it. The Gerbils need to be in an old fish tank with the lid secured by heavy books to stop them climbing on the water dispenser and banging their heads on it to get out. They feed from a 7" soup plate, once daily.

Wish I had started this programme a year ago.
Recommend.