flowerqueen

The only filters I own are Cokin p series nd grads. I would like to try some long exposures of the sea, can anyone recommend a filter? I can't find the Cokin equivalent of a lee big stopper.I have found a Tiffen 72mm APEX circular LE filter, but I can't find any reviews for it. Let me know if this has been discussed elsewhere on the forum - I did look, but it is late and I have probably missed something! Thanks.