I have been using one of these for years. It only holds 4 liters at a time so probably only suitable for smaller aquarims, mine are 30L. There is a tap so you can adjust the speed of the drips, or even slow flow. I use it for water changes and acclimatising new shrimp. Made in USA www.zoomed.com so must be available there, and meant for reptiles? https://amzn.to/2Dc3oVp The link is just so you can see the product from the UK place I get them.