i will think on this one. first i have to figure out where in the heck im going to store 75 g of salt water thats in the test tank! lol then i can work on a beter more refined version of the impellor . after that then i can get to the venturie design. that might work well. we will see. i want to see if sequence will send me a couple of impellors to work with. i think the 4300 would work better. what do you think? i also have to work on getting my 20" acrylic tube home so i can see how it works in a shorter fatter design. say 20" diam 4 ft tall.ya think it would work? or do i need to tear into my second dart and modify that one too?