How deep is your tank Frankie?
Usually on tanks 24" deep & 4ft long I say go with two 250w mh's reeflux 10k's or the XM's If you want higher PAR. In your case your supplementing with T5's & they look really blue, If you add another 20MH I'm sure it will wash out the 10k XM's LOL I would have to see what they look first before adding another, not sure on the PAR for 175w, but you do have good lamps so I'm sure it is up there. The 20XM's have produced crappy PAR in most test I've seen, not sure how well 400W's would produce but with all of the other lights I think It may be just right, you may want to get a 250W Reeflux 12k in the middle instead, We have a thread with comparisons & better performance PAR wise, so it might be worth looking into. First I'd check out what it looks like with the MH's tomorrow.