Ok so some tips on the sand pit.... if you buy a clam shell... job done, LOL!!
If you decide to build one like we did, don't put the black lining up the sides as when they find it, they like to tear it off, then they realise it's also at the bottom. Needless to say I think there is enough sand there that the weeds and stuff won't get in but it's nicer to know it's lined.
So far so good with the cats, checked again this arve and nothing untoward in there.
Thankx again Shelby, I'll let u know how i go