I did my first proper full water change on this perch tank this morning. I did a partial one last week but didn't touch the filters. There was a major surprise, but after thinking about it for a bit maybe it shouldn't be a surprise at all!
These perch are only fed live food. Worms, crickets and mealworms. Absolutely no shop bought flake or pellet enter this tank (I do feed my old fish food to my crickets and mealworms but is that the same as feeding direct into the tank???)
What I couldn't get over was how clean my very fine second stage mechanical sponges were. When I squeezed them out in a bucket the water wasn't that dirty at all, unlike my old tropical set up where the sponges would be full of slutch. The water would be black with fine particulate from my tropical set up.
However, my coarser first stage mechanical sponges were heavily clogged up with coarser particulate, a lot of uneaten bits of worm and cricket wings etc. The coarser sponges on my old tropical set up were a lot cleaner.
In short, there has been a complete change around between where all the crud collects between the tropical and cold water tanks.
And then it hit me, it became very clear as to what has gone on here, and it doesn't say a lot about the quality of shop bought fish food, and let's face it, we already know that the vast majority of it is extremely poor quality anyway.
It would seem that in this coldwater perch tank a lot more of the live food I'm feeding is being absorbed by the perch resulting in less waste to build up in my mechanical filters.
Whereas in my tropical tank the vast majority of the mass produced shop bought flakes and pellets were not being absorbed by the fish, simply because a lot of it is filler!!!! It was simply being shat out by my tropical fish and collecting in the fine filters.
Could it well be that all the slutchy crud in my fine sponges from my old tropical set up was nothing more than the filler from the food? It makes complete sense to me.
Thoughts???