swimming pool for tortoises

I thought I would let you know the easiest way to put a pool into your tortoises pen. Firstly get a large cat litter tray, the plastic ones.  Dig a little hole and place the tray inside.  Put  stones or  slate  around the outside  to about a foot around it. Then put stones or slate into the tray about half full (enough so that the tortoise can get in and out easily and won't get stuck) Then fill with water and put your tortoise into the pool  so that it gets used to it. You will have to top up daily with clean water and sometimes if the  stones inside the pool go green then all you do is put some bleech into it and leave for a while, obviously make sure your tortoise is out of the way why this is being done; I usually do mine at night when they have all gone to bed. Leave the bleech for an hour or  so or less once its done the trick then  clean thoroughly by leaving the hose running until the froth goes away. You will find  once they know it is there they will sometimes march straight over it and other times wallow for ages!!