powerhead

Does anyone have a trick to see how your tank is flowing with your powerhead locations? I watched a video were someone put glitter in there tank with only water in it. This was cool but probably not a good idea for a set up display tank. Any Ideas?

I have a bnib mp40qd for sale I bought it back in June for a build but am going a new direction. I'm asking 300 plus shipping and you pay fees. Can ship out tomorrow if paypal before then of course I look forward to doing business with you.