Hi I am new to the reef community but am willing to learn a lot from here. I just purchased the WD 100 CS filter which has an open compartment for return pump and possibly a skimmer. The dimensions of the whole filter state 18L x 12W but the actual open space is roughly 11.5L x 9W. The psk 150 foot print states 12x6. which is .5 inch longer than the area. Does this mean that the skimmer willnot fit or is there a chance that it will fit. Iam setting up a 75 gallon FOWLR but need a strong in-sump skimmer so the PSK 75 is out of the question. Does anyone know if it fits in the alotted space. I dont want to return my filter and I need a strong insump skimmer. Thanks!