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View Full Version : Help needed: Any mechanical engineers? Physics teachers?


Lavoisier
11/25/2011, 12:01 PM
I have used a diy surge (5 gal flush bucket) on my 90gal for years and love it. I recently acquired my 180 and face a dilemma--whether to build another surge bucket or go with a wave maker and Koralia powerheads. I have a 20" space between the top of my 90g and the bottom of the surge bucket but I only have 11" between top of 180 and bottom of bucket. Can someone compare the force of the drop between the 20 vs 11 inches? Will 11" with a 2" drain provide enough surge? How much more force would I get with a 3" drain with 11" drop?

I wish now I had studied harder in my High School physics class!

kcress
11/25/2011, 03:28 PM
If you lower your bucket by 1/2 the distance everything else the same you will have half the surge forces.

Changing from 2" to 3" doubles the flow - hence surge.

Lavoisier
11/25/2011, 04:22 PM
Thank you, dilemma solved! I will go with a 3" drain and should have about the same effect.

kcress
11/25/2011, 06:40 PM
Are you taking a Bourneman or Carlson surge? A Carlson is an auto-siphon and a Bourneman is a toilet valve with a float.

Lavoisier
11/25/2011, 09:19 PM
I think an Carlson--an auto-siphon, though I did not know its name until now. It is not a toilet valve but a U shaped 2" pvc pipe in the 5g bucket.

kcress
11/25/2011, 09:43 PM
Yeah, that's a Carlson.

Well.. What are you going to drive it with? You need heka flow to initialize a 3 inch siphon. You actually need a bunch of flow to even start a 2".

Lavoisier
11/26/2011, 07:54 AM
I will use my Hammerhead--it already gives me too much flow and I have to "throttle" it back. I'll put a 2" to 1" T on the return and hope that puts enough water in the bucket fast enough to start the siphons. I use the same type of set up on my 90 (Blueline 30x) and actually have two "T"'s (one to the refugium--restricted flow--and then I had to use a return to the tank because too much water was entering the bucket too quickly. However, you make a good point with the three inch return, the flow increases twofold, so i'll put it together and see what happens.

kcress
11/26/2011, 07:47 PM
A hammerhead should certainly be enough.

Hope you can provide pictures. I'm always interested in generators of whatever type.

You might also consider smaller, like 1-1/2" but run dual units. One on each end or even both on the same side. With them running asynchronously the dynamics will look interestingly random. I suspect 1-1/2" will be just enough for a 180.

Lavoisier
11/27/2011, 06:27 AM
Dual units is an interesting idea, I may give that a try as well.

Do you think starting with a 3" drain then reducing to 1-1/2" as it enters the tank would interfere with the siphon? I am thinking with only the 11" drop I might get more force moving water with the restriction.