Advise needed for a tank change and hardware please.

[Ruth]

Over time your sand bed will trap a lot of crap. It is OK as long as it is not disturbed (to a point) but as soon as you disturb it, it will release all the nasties. If you want to see how bad it is once you have moved all your livestock and live rock etc. and just have an inch or 2 of water and sand in the bottom of your old tank give it a stir and take a whif - then let it sit for a couple of days and test that water (the stuff in your old tank). If you get ammonia and nitrite readings that is your answer.
I know when I move or sell my 230g tank that has a 4" sand bed that sand is going in the garbage unless the purchaser wants it.
FWIW that is the only large tank I have sand in and would not do it again. BB all the way for me.