Of course, that is a part of regular routine.

Even a big canister filter does not replace a manually exchange of water once or twice for a week. And I think that it was a really lucky product from Exo Terra company for turtles. (for example, the turtle cliff of Exo Terra is not so great - I removed it from terrarium.) To tell the truth, a seller in the pet shop tolds to me that I definitely must to buy a large tank immediately. It sounds like: "you know, it is a big economy in money. You can buy just one tank for the future." But the technology support group in Exo Terra company was right about size of turtles terrarium. There was a second size of the terrarium but is more heavy for me.
Oh! First question was about why?
First step - laundry detergent can remove just organic parts of dirt. second step - deep desinfection with cleaner gel (It can be deactivated by organic dirt - because of this reason it is second step) and third - just to try sterilization by boiling water.
The mobile terrarium is more safe for little turtles exactly by the possibility to easy wash it.
Here is ~40 litres = ~>10 gallons. Usually, one turtle at a time swimming as others sitting on the Islands
