You would like to have about 450-480 gph
on your filter(s). When you add all your media, tubing, media and U bends in your tubing, you are looking at a 50-60% reduction of flow. This would give you your 4-5 times flow rated recommended after the reduction. What's more important is the media you use. Never use any hard, non porous media as water just goes around that stuff. You need good media where water flows through the media at all times like 10/20 ppi foam or simple pot scrubbies. Two filters... up to you.