I don't know why it died but i found it upside down on the bottom of the tank. The other turtle seems kind of "Depressed" (YES, I know, they don't get depressed, but its the only word that sums up its behavior.) My dad blamed the death on me having to change the tank's water 100% every month. I was kind of confused since the filter I use needs to be cleaned out once a month anyways, and by that time, the tank could be a little disgusting under the rocks. But my dad suggested that I only replace the water 50% at a time... I forgot his reasoning (something about air, or not.. idk), but it seems ridiculous.
Is this necessary? and my turtle's about 4.5 inches long.
), it is best to do frequent small water changes. Something like 10-20% a week. That way, the beneficial bacteria that keep your water clean don't have to re-establish themselves every 100% water change. They get to keep their supply of food if you only replace 10-20% of the water, while you get rid of some of the other harmful things in water that simple bacteria don't get rid of.
and since it died on its BACK and found at the bottom of the tank, do you think its more likely that it drowned? I did change the water.