Ive built and used a few of them over the years,almost all were carlson type.
The last one Jamie and i put together, wich consisted of 2-5 gal buckets, plumbed together at the base, for almost a 10 gal surge on a frag tank.
That one in particular worked a little too well, i was trying to keep 200 frags from piling up at one end...
These buckets bases were about 40" up from the 1.5" output...the resulting surge was enouph to push the length of pipe sideways 2" during discharge.
I have also built a four stage one for a wholesale distributer for use on their SPS holding system, using a 100g arylic tank divided into 4 sections, each of these delivering a huge 25 gal surge...at the end of each cycle you actually FELT the siphon break.
I bet this could easily be done with a smaller tank delivering consistant but smaller surges.
I have noticed they are Very reliable, i dont think ive ever seen one stop working or fail to restart...something i cant say for flapper methods.
Bubbles and noise are their downfall, and ive tried the airline, aswell as angled siphon end....they work to a degree OR for a length of time before becoming clogged.
On the 5 gal buckets, lids were used to help, but still very loud at the end of a surge.
Like mentioned, probably better off to save for a tunze, but you still will never beat a surge like that while only using a small powehead to run it.
I kinda miss watching it actually....wheres those old pics.
Cheers, Marc.