redearslider.com

Working with two aquariums lately, a 55 gallon and 20 gallon. Each one a home to a approximately 7" Red-eared slider.

Filter of coice on each is a FilStar XP-M aka XP2. On the 55 gallon I vacuum twice at least twice a week which ensures some water gets changed. Any surface oddities can be resolved with a bubbler or by reducing the water level by 1 inch to allow the agitator to agitate the surface properly.

The question really concerns the 20 gallon. Yes I know, poor girl should be in a larger tank. It's in the pipeline, priorities are currently focused on strengthening her up and preventing illness. The water in this tank, is crystal clear since installing the filter nor does it smell.

If the water is clear and doesn't smell can I simply replenish the evaporated water or should I actually remove some even if there is nothing to vacuum?

I'm not really sure, but I know that even with a filter you should usually change the water once a week. What I do is add water whenever the water level seems too low, and then when the water change day comes I take out almost all the water, and put dechlorinated water back in. I would change the water even if it seems clean or doesn't smell, just in case. I don't know, that's what I do. Hope I helped!

I agree with hi9215... do the change regularly regardless of how it looks. The more water you have, the few changes you need to make. With an appropriate sized tank and filtration, you might only need to do about a 25% change every 2-4 weeks. Since the turtle is in a small tank, no amount of filtration will help remove things in the water you cannot see. So I would think that at least weekly changes are required.

Thanks guys. I went ahead and did 50% water changes for both of them.