Hi guys
I have personally used milk crates myself, Have even gone to cutting out pond liner and sticking it on the inside of the milk crate.
Stackable containers have a slope where the bottom of the container is shorter than the top this allows the water to drop in the mid areas of the next container rather than the sides this is very important as a lot of water can just run down the sides and continue to run down the sides of the next container.
I have also tried drilling holes in containers. I prefer to use the milk crates as the wholes are large but more importantly the actual surface that is physically touching the media is smaller than say when you have the bottom of the container with holes. when you place the media directly above drilled holes you will find that some debri remain trapped in the container in spaces where there is least turbulence or greatest resistance of flow down to the next container.
Like JG said just get a plastic container of the right shape cut out the bottom and visit your local steel manufacturer and get a stainless steel grid with square holes that are large and where the metal is only around 2mm thick.
With showers or ponds that use showers if you have an area of space that allows some degree of settlement the fines will always settle there even if you have great volume turnover this will affect the clarity of the water.
The whole concept of a
proper bakki shower pond is there is no where for the fines to settle ie pond floor is sloped to the bottom drain. Bottom drain is connected to a small pump chamber using a submersible pump that sucks from the bottom of the chamber there by preventing settlement and up and over the showers. Obviously there should be the right amount of media and appropriate flow rate, not too slow and not too fast. For every 1 ton of volume turnover you should have 4 to 5kg of media. That is for the most optimum setup, for eg 10 ton pond with 30 ton turnover (say 24 ton through bottom drain and 6 ton through skimmer) with around 120 to 150kg. A simple and elegant system (saves money on building too
TEWA