The design is horrible.....unless I am doing something wrong. The lid fits over a 3/4" pvc tube that is supposed to direct the water to the bottom of the reactor, where it then is forced upwards through the media. First issue is half of the water doesn't make it down through the tube because it isn't air tight.....you can see it pouring directly into the reactor chamber if that makes sense. Also, there is a rubber O-ring that holds the upper media plate and sponge in place so that the water being forced upwards doesn't push everything to the top. The O-ring is extremely difficult to get on and pushed down (in my model at least)..... I have to use two wooden spoons and try to force it all the way down on the tube because my hand doesn't fit into the chamber. This only applies to the carbon since it needs to be sandwiched between the two sponges but it is ridiculously cumbersome to change the media. I miss my BRS reactors lol. They do look nice and match my sump though.....;) I have emailed Bashsea twice with no responses as of yet.
