Thanks once again guys. I understand what you mean when you say it's not perfect. If there was a perfect one, I wouldn't need to be in this forum
Thanks for the pics Seattle. I like the look of all the substrates but the STS looks like it has a nice particle size to it. Wish I could get it here, would make things easier. However, the cat litter I mentioned seems to be an ok option too. I may have to test it out. Not sure what the colour of it is though. I'll sift it first and then wash it a lot. That should help, hopefully. We have a new kitten, coincidentally, so it may be worth a try anyway. Even if I just mixed it in a glass of water and had a look at the colour, etc. I saw someone use it in their layer of miracle grow in a video and in a post on a forum. But someone else said they capped with it. I'll have to read the bag too, hopefully that has some answers.
Hmm slate? I thought that would be fairly inert. Didn't know about that. I'll look into it. Might even have to check out the local baseball fields...
I won't be able to do any elaborate tests when I use the clay, so I am hoping it won't change the chemistry of the tank too much. I will have a continual drip system for water changes and the tank will probably cycle like 4 times a week or more (couldn't get a slower dripper), so hopefully the extra water changes negate the litter's high CEC.
Then my next problem is making diy root taps!
All this for a turtle I got when I was young....
After this last year I have learnt so much but it always seems there's another problem around the corner!