sari said:
Interesting! I completely agree on the mature filter business and of course the ammonia and nitrite spikes harm fish. But like said, new and unestablished tank can successfully sustain more demanding fish as long as there is a mature filter inside. What I meant by some tanks never establishing was with some hobbyists not treating water, using all sorts of chemicals and washing the filters in hot tap water etc when the bacteria has never a chance to develop and ending up having a forever cycling tank.
Right, I thought that's what you meant.
Want to hear something that many 'experts' would throw their hands up at?
I wash the sponges on my filters in tap water...
Two reasons why I can do this.
First my tap water seems to have very low chlorine - I haven't needed to use dechlorinator for years (I do recently use RO now on my tropical tanks though).
Secondly I never rely on just foam to biologically filter. I don't think you should combine the mechanical and biological elements of filtration if possible and always look for a filter set up where I can separate the two processes. This is a hangover from my koi filter knowledge/experience where you want mechanical that is regularly cleaned that removes the physical waste and doesn't encourage a bacterial population that will be set back everytime it's washed (even if you use pond/tank water) and then biological filtration that is settled and undisturbed and doesn't collect waste but allows it to go through the biological media.
So I view foam in my filters as the mechanical stage and therefore do not really want a bacterial colony there and, while I know it does develop between cleanings, I'm quite happy to remove a lot of it at every cleaning and rely on the bacteria in the sintered glass or other biological media.
Also do not discount the effect of an established tank as well as an established filter. Like George I've set many 'new' tanks up and stocked with 'delicate' fish after only a few days, but I follow that up with large regular water changes. I've also seen the difference between a tank with gravel or sand substrate and a bare tank. The bare tanks are much harder to maintain as the water quality see-saws all over the place. The extra surface area of the sand/gravel makes a big difference with the higher bacterial population in the tank.