Sorry winset, that sounds a very strange request to me! - I've had many freshwater tanks in the past, and always did my best to hide everything. I always had under gravel filters, and I think the best pumps were Zoobeco (or something like that), - because they were the quietest, and in addition, I stood the pump on foam rubber! (out of sight of course) - The result was no visible filter, and no pump noise!
There is enough noise from the computer fans etc. - I wouldn't like to add the hum/buzz of a pump, - sorry!
I do like bubble sounds though!
