1- If I use a 6” (152 mm) lift pipe and reduce to a 3” (76 MM) PVC under the gravel (these will have 3/8” (10 mm) holes drilled every 175 mm in it to pull water down through the 6” (150 mm) of 3/4” - 1” (20-25 MM) gravel layer).
1a- Will reducing from a 150 mm lift pipe to a smaller under gravel pipe create a higher velocity of flow in the smaller pipe like a smaller hose opening does on a garden hose - but in reverse?
2- Does using a larger lift pipe - say 150 mm instead of 100 mm create a great deal more lift in total volume of water moved? Does it take a lot more air to power a 150 mm over a 100 mm pipe - is it worth it? How much more?
3- Pressure chamber question. On the videos it looks like the pressure chamber is very “thin” - 6-7 mm. Is it important that the chamber is that small or could I use a 100 mm lift tube and a 150 mm chamber?
4- do yo have a formula for how many holes and size of holes for the pressure chamber to tube holes?
5- how many holes/liter of air flow? Is there a formula?
6- Air Lines: how far can I effectively run an air line? The pond plan is quite large - around 45,000 liters. There is a small building that I want to put my air pumps in and it is about 10 M from the lower end of the pond. I think some of the air lines might be as long as 30-40 meters. Will I lose air pressure over that distance? The lift tubes will be almost 2 M deep.
6a- I am trying to produce about 40,000 liter/hr total flow through the under gravel system and would like to do it through two lift tubes.
7- There are a few people here doing under gravel filters in ponds and they seem quite effective. This pond will also have a large bog/wetland filter - about 3 M x 5 M and 1.5 M deep. I know on gentleman outside of Chicago that has a 27 year old under gravel filter set up that has run trouble free for that entire time. They are all running on traditional pumps that are 400-600 Watt motors. The idea of running the same type of flow (it might take 2-4 20 Watt air pumps) for a small fraction of the cost is very attractive. I plan on putting a diverted valve in at ground level for winter aeration at a shallow depth that will turn off the lift for the winter.
I will be grateful for any help and advice you can offer. I appreciate your ideas. I would love more videos in English
. Thank you for your help
John
*** One last question. In the videos it looks like everyone builds these with an two air release pipes/vents prior to the outflow of the water. What is the reason for this? Just bubble reduction in the pond? Or is there a flow change?
