I've used this technique 2 or 3 times over the decades. Ideally when a tank starts leaking it can be emptied immediately but sometimes the combination of time, logistics and stress to the animals from being moved multiple times make it preferable to leave everything in place for a day or two. A freind had a 20+ year old tank start leaking and since a new tank could be bought and installed in a day or two we left everything in place until tank could be replaced and jsut used a strip of towel to wick water into a bucket.
