I just built a DIY moving bed filter using K2 media (about the same size as K1 but with a 5 spoke inner design as opposed to 4 spoke with a bigger overall surface area) in a 30 gallon barrel.
I have an EazyPod with K1 media in it (couple of years old) and a Helix bed filter with K3 media in it (about a year old).
My DIY filter has 2 cubic feet (about 56 litres) of the K2 in it that is now three weeks old.
The attached picture shows the K2 at the bottom left and it is the lightest color of the media with a green coating starting to appear on it.
The K1 to the left has a very dark brown color on one of the pieces and a darker green and more dense covering on the second piece.
The K3 (larger media) also has a denser green covering.
The K3 in the helix is the same green color / density as this piece.
The K1 in the EazyPod is just a dirty white color, so I assume not much of a bio colony due to it being largely a mechanical filter in my case. It is fed by the bottom drain before an external pump -> MC50 -> EVO 55 -> Helix moving bed waterfall filter.
I seeded the DIY filter with some K1 from the EazyPod (a few hand fulls over about a two week period) and about a dozen or so pieces of K3 from the Helix.
I have never had any of my media turn the dark brown color before, is this normal and is this good? I have seen pictures of K1 etc... being a light to dark tea color. Is the green color showing a good bio film or is that just algae and the bio filter is not working efficiently?
My pond is pretty heavily populated with 25 Koi in about 4400 gallons with filtration. I added the additional bio filter due to having a struggle to keep my ammonia readings at 0.
When I re-did the pond about a year ago, I added the Helix moving bed filter waterfall with the advertising stating it could process the waste produced by something like 1 1/2 lbs of food. I started to wonder about this recently and with only 15 Litres of media in it, didn't really see how this was possible. They recently updated the information to indicate 1 lb and have now updated the information on the filter to indicate it can process the waste of 1/3 lb of food daily. Based on the info I thought I had plenty of bio, but make sure you check your info whenever you can. According to the EA website, 50 Litres of K1 can process the waste for about 0.55 lbs of food daily.
Anyway, hopefully I have the bio covered now with the addition of the