ok.. ya it makes sence, but you would need two units one for suction and one for discharge, how would you actuate the suction one? I could see it maybe working by using a self priming pump and installing it upside down, but now were talking a more expensive pump which will require more maintance and is supseptable to dammage from depris.

I think the simplest way still is by using two actuated ball valves. 5 second switch over ports are never blocked while switching over so even if there out of sync by a few seconds it will still work fine. one timer can seitch both. with two timers one for the actuaters and one for the pump you can get your 5 hours one way, 1 hour dead, 5 hours the other way easily and you can customize your flow very easily also.

but to get a true lamaner flow accross the tank its going to take a few holes in each end. I am looking at six 3/4" bulkheads on each end of a 30 gal tank a bigger tank would use bigger bulkheads but I would still use at least six on each end. so this could get expensive for drilling. then you can size your pump output so you get no more than 2 or 3 PSI at the output of the bulkheads so you don't blast anything. this combined with the suction on the other side will make the nice current through the tank.

If I had to I could dig out my fluid dynamic books and figure it out but it is a lot of calculations and sometimes FD makes my brain hurt :mrgreen: thermal dynamics is a lot easier for me:wink: some times it is more easy to put a bypass to the sump on the outlet of the pump and just adjust it to get the strengh of flow your after.. I know its a lazy aproach but it works :redface::mrgreen:

Steve

Let's back up for a moment, this design was for Mitch to find an inexpensive way to redirect the flow for MitchM, he simply wanted to change direction every 5 hours from his sump return this will work for him.

I will answer your laminar flow questions in another post to avoid confusion

Paul,

So basically that unit that you show in the animation would be mounted in the display tank and the direction would change whenever the pump turns on after the rest cycle?
What type of GPH can that unit handle?

http://i1008.photobucket.com/albums/...tleswitch2.jpg

You would need a blocker in the shuttle of course :)

Paul

This would mount onto the pump and be plumbed with 2 pipes back to the left and right hand end of the tank where you wanted them.

You make it as large as you wish to suit the pump, 1 1/2 shuttle for Hammerheads Ampmasters Darts etc, and make it out of 2" for pumps with larger capacity.

Would drain back from the main tank affect it's operation at all?

If you had the room you could have an overflow on each end of the tank to pull from. With a pump on each end pulling from the other sides overflow, would ceate great flow. Thats what I'm planning to do for my new tank.

I highly doubt it, your outlets would have to be near the surface anyway to prevent a siphon in case of a power out, you could even mount this thing in the top middle of the back of the tank and simply feed left and right, it would be a better solution.

If you say check valve I will come out there and smack you.

lol...I had a check valve.......once....

I was wondering if the pressure coming back would somehow move the position of the unit.

I haven't located my sump yet, so there is the option of mounting it pretty close to tank level. 40 gallons or so of drain back wouldn't be a problem.

You don't have any existing units that you have pictures of do you?
On your website I see the Revolutions in action, but they are mounted in the tank.

I have never built one, I just invented this just for you, trust me it will work fine, I did some R&D back when I first dremt up the revs, lots of different designs and this was similar to one of them but in a much smaller scale.

I have revs still working away with over 8 million cycles on them.