I noticed one of my budgies eating the seed mix from the dispenser and that the clean lining I put in their cage yesterday has been torn to shreds once again, I think that may be the cause of the odd poops since coloured ink is in the paper. I'm going to look out for alternative lining.
Nicalou, just for reference in the future, I emailed the vet clinic you mentioned you took your rabbit too.
While they don't have an avian vet on staff there as she works at the Scunthorpe practice, they are prepared to have her travel to the Market Rasen practice, should you need to see an avian vet.
What i was recommended from my vet was white paper which you use in printers ( with no color on it ) or white kitchen paper which can absorb urine .... these also help watching better their urine ( color mostly ) and poop even the slightest change .. also you may not let them come in str8 contact with their poop ( if there is no protection at about 1' at least from them and the bottom plz do so .. )
There are other things you can use as well such as sand , but with caution and never should they come in contact with any lining material or poop ....
Personally i use kitchen paper ..
Placing the newspaper, craft paper, or butcher paper on top of the bottom grate in the cage is perfectly fine as long as you change the papers frequently.
I personally change the papers in my birds' cages each morning and evening.
My birds get their morning fresh seed ration spread on their clean papers which stimulates their natural foraging instincts as well as encourages them to use the entire flight cage.
I wouldnt risk between morning and evening my budgie having a taste of a piece of " cake " .... or early in the morning .. since im not next to them 24/7 .. And i wouldnt consider it as the best i can do , to avoid it .. ( ex he drops a piece of veg on the poop he get down he eat it .. )
I did never say grit or regural sand which is just stones i said " surgical ".... the sand i mentioned is made from sea ostreals , which are also contained in many seed mixes and it has minerals and Ω3 oils ( it also helps in the breeding time for the hen to lay eggs and my vet used it back some years with oil extract to help a budgie lay an egg which was stuck .. and woala in 6 hours there it was we saved her .... a lot mistakes back then .. ) its a little bit expensive though .. but it absorbs smell , urine , poop etc and I wouldnt recommend it since it doesnt help indicate the birds poop everyday ..
I just mentioned my experience and position on this , a little bit ful analytic but i saw there were some misunderstandings ..
At least you got many alternatives other than what you are now using ,
Hope we really helped you Nicalou : )