Looks like the floaters are maybe salvinia minima, they're great (and much less messy than duckweed)!
That sounds reasonable. In the meantime, I'll keep an eye on the KH level. If the sea shell rock isn't raising it sufficiently by the time the lily reaches 6 inches (the approximate distance to the surface) I'll consider adding some crushed coral or something. I have the salvinia to think about too.Oh, the lily will live off the bulb but after a while it’ll need nutrients.
So, one question came up on another fish forum concerning the role of beneficial bacteria (BB) in the water column. The other forum which can safely be characterized as a Nitrogen Cycle hub, the insistence is that BB only exist on things : the bio-media, substrate, decorations, etc. And, that the water column has to be filtered through it. But, I question that since I've had no filtration for almost two months and cycled fairly quickly (two weeks) with nothing more than 7 gallons of standing water and five zebra danios. Oh, and four lucky bamboo plants. Is it possible for lucky bamboo to convert that much ammonia that quickly or can "floating" bacteria contribute its share to the nitrification process?
Thank you very much for returning to one of my earliest questions. When I took out my old bio rings which had just been sitting at the bottom of my bowl in their old basket, I thought - as you did - "They're not doing me any good there. Might as well put them away until I need a filter again." But, nearly five months after my last successful nitrogen cycle, I have no idea what's maintaining my nitrate level at 20 ppm despite 8 or 9 partial water changes of 20% each?When i was searching about this topic i came across a paper that measured beneficial bacteria in the tank (it was really focused on substrate vs filter) and it found that the bulk of the bacteria was in the filter in material like the sponge and the substrate didn't have that much.
However the paper didn't really answer the question of what is sufficient beneficial bacteria and if it will reside on plant matter or similar. I know there are a lot of people with larger tanks (300,400+ gallons) that can run a tank just fine without a filter as long as there is adequate filtration (one discus keeper was telling me about his 400 gallon tank). This doesn't really answer your question nor does it answer the question of where the beneficial bacteria is in his tank (he had a very strong pump (I think it was 800gph but maybe 1500gph) that pulled the water from the bottom (the tank had two holes in the bottom - one input to the pump and the other output but no filter connected to the pump). The description isn't exactly accurate because there is a raised inlet outlet connected to the two bulkheads that goes above the substrate.
Anyway I'm not sure the beneficial bacteria is actually in the water column but i'm pretty sure it does require some circulation of the tank water.
It still begs the question just how much do you need. In my smaller tanks (40b and smaller) i just use sponges but my larger tank (120) i do use an fx6.
Also i think a bit depends on fish load. 5 zebra danios is pretty low bio load.