Thanks yes I appreciate the details you have mentioned, once we get to a position of being able to buy the pipes and fittings I was going to ask before I buy.There's a bit more to it then I have mentioned like how many pipes for the size of the shelf. Cutting the pipes instead of drilling holes. Possible clean out pipes at the end of the pipes. How much flow to send down the pipe for the size and length of the pipe . The size of the rock. Its a pretty simple process but to do it right requires a little more planning and discussion. Your pond is so big you need every ounce of bio you can get.
What does the air pump do now ?
But I will ask now,
How to calculate what size of pipe and how many per shelf?
I intended to cut slots in the pipes on the under side as you suggested earlier but at what distance apart?
And most importantly what would be the output from a pump that has to supply the water flow? My current pumps each put out 64m3 per hour that is around 16907 gallons per hour each. The model is the Tsunami MBA 1500s submersible pump I have 2 running.