lots of random things about siphons

[Joseph Michael Martino]

i have a fish pond in the ground, one bed about 4' above the pond, and one bed that i will have to quite literally put directly on the ground. too low to the ground to get an auto siphon to work properly, but, i was thinking i could use a tube weir, a u bend, or an outside loop.

basically looking for anything that allows me to drain as much bed as possible, without having to have too much going on underneath the bed. Im leaning towards the tube weir, but understand that its typically used for raft systems; anyone see any issues with this or have any thoughts?

had some questions about building a siphon and other questions as well!  If I want to build a weir siphon, are there any ratios for size of bed to size of pipe?  Are there any ratios for size of bed and number of siphons?

would the u bend be better? itd probably be easier for people to visualize with a picture, but i dont have one as of yet...my main concern with the u bend is that if it comes out of the side of the bed, i will have to put too many 90s in it to reroute the water to the pond, and if i put it directly on the front of the bed, that it will risk being stepped on or damaged by someone working on the bed above.

also, this is random, but would anyone advise me on the use of PT lumber to build the media beds or pond?

thanks for your thoughts!