Dan,

I had the same thoughts as you, however, my pond guy - "has done 30 or 40 fo these" claims it works. I looked at a couple of his ponds and he seems to check out, overall. Havent seen one in sipohn mode yet.

I agree the question of the design is: Will there be a siphon when the water hits the 4" pipe OR will it suck air and just drain...(not sure I will be able to visually see much difference?) hopefully I will find out soon. Not much rain in the forecast right now.

On the question of the size of the 4". I agree with you, a smaller pipe would work. I never really asked "why" a 4". I suppose that was based on avaialblity of the pipe joint and/or habits of my contractor. One thing I have noticed about contractors is that they seem to find what works for them and stick with it.

I suppose if the siphon doesnt engage as planned - I can cut the 4" pipe down or replace it...there is no real reason to have a pipe there other than to eliminate the hole from becoming clogged.

- Smoke 'em if you got 'em

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