its only a guesstimate, note the "possibly 3" before you try and get smart, not an exact figure. jebo are cheap, and to some extent you do get what you pay for, but these are great for the money you pay and obviously not the quality of eheim which is why i also mention ebay for 2nd hand eheims. rena are not a bargain basement filter for a tight budget. i dont live in N. America hence the "could get 2 or possibly 3". some key words in there to take note of.
i was mentioning that if the budget is that tight then jebo are good and rena are far from the budget ranges.