"I had bought a much cheaper version in the past, and had very poor results--I needed something to clean the sludge, and have had a Python system for several years---The only "problem" with the Python, is it removes the water too fast, so I could not get a proper cleaning job done without draining, filling, draining,filling, etc., over and over---not only very time consuming, but not the best thing for the fish!! So, I had been looking for something like this, and found it for twice the price on another site, I decided to "Google" the product name, and up pops Petco! I am sooo glad it did! Not only was/is the price much better, but for the use I had in mind, this is great! It doesnt remove the water, has excellent suction/cleaning power, Is lightweight, and very easy to use! It also comes with plenty of length, which you can shorten or lengthen to fit almost any tank out there---I have 3 tanks, including a difficult to clean corner unit---This sludge remover will do all you hope--It doesnt disturb the lower layers of beneficial bacteria, but removes as much , or as little, as you like--- The filter is easy to remove and clean, and with a gasket sealing system that actually works, you can leave the unit totally submerged in the tank, while you remove and clean/replace the filter---saves time, and you dont have to carry a dripping, wet, nasty tool through the house! I cannot say enough in praise of this product---simply a fantastic tool that every aquarium owner should consider!"