Change of filter media to all foam has affected nitrates unexpectedly !!!

[hamfistUK]

From that website, the author makes this one point:
Natural layers of biofiltration are usually undisturbed for longer periods of time (many weeks and months). In nature, no one squeezes out the debris or rinses the media on a weekly schedule.

I am going to experiment, I have two canister filters. In one, I am going to use all Biohome Ultimate bio-media, and in the other, I will use bio-foam. I want to see which one works better to eliminate nitrates without chemical filtration.

Important point, and well made ! I'll look forward to hearing the results of your test !

So do not clean filters unless they need it, which they all will sooner or later. Do change the water regularly.

Exactly. However, I know that I do have a slightly clean-obsessive personality and have a tendency to clean out my filters too often. In fact I just completely cleaned the media in 2 of my 3 canisters on my big tank. It'll be interesting to see if that affects the nitrates, as I am now convinced that I had great anaerobic nitrate-removing areas going on in them with really slow flow areas of mulm build-up.

FYI, that website for Biohome Ultimate has this recommendation for Eheim filters with layers of foam placement on the bottom of Course, Medium, and Fine: https://greatwaveeng.com/eheim-filters/

I know that's always been the "traditional advice. I must say that having coarse 20 ppi foam only has always worked perfectly for me and I like the convenience of the larger pore size not clogging up or slowing flow as much as finer, 30 ppi foams.

 

[TwoTankAmin]

The thing one needs to know about the cfacultative bacteria is that they are much slower to got to work than the nitrifiers. So, one needs to be patient as it will take some time for a large foam media to become well colonized with a full complement of mircoorganisms and for the selective areas of the foam to become anaerobic.

AS for the choice of pore size. I like the 20 ppi. The 10 is great if one is doing layers of media or for pre-filters and tank dividers. But for my filters I tend to use all 20 ppi. As noted, it doesn't clohg as redily as morer pore per inch sizes which in Poret are available up to 45 ppi. I use the cubefilters rather than other spinge filters and in a few tanks with smaller fish I have a couple of 2o ppi cubes. But the 20 seems to be the best compromise between pore size and how often they need to be cleaned.

I rinse out my few remaining ATI sponges weekly but the cubefilters are onlt rinse monthly at best. I have the 3 basket Eheim canister which was supposed to be set up with all Poret foam.The plan was to have the first layer be 10 ppi and the rest 20. But that project never got done and I still have that Pro II 2028 NIB on the shelf.

 

[StevenF]

In most aquarium the water is well oxygenated the bacteria consume most of the organic waiste. So it is reasonable that the organics (fish Waist) are also at very low levels. But since oxygen levels are high nitrate is not consumed. Only plants and algae can consume nitrate in high oxygen levels. And if there are no plants all the other nutrients bacteria and plants need are probably at sufficient levels. the bacteria was everywhere in the aquarium including floating in the water.

What probably happened when the foam was added to the filter The foam filtered out a lot of oxygen loving bacteria which then then died leading to low oxygen levels in the foam. the dead bacteria became food for the nitrate eating bacteria. They consumed the nitrate leaving behind nitrogen gas which leaves the water and disperses in the air.

I suspect that for this to work best the water flow through the filter has to be very slow. Much slower than what is typical of most aquarium filters. High water flow means high oxygen levels in the water. In addition to the foam you might want to put a food source for the nitrate consuming bacteria. Such as wood chips. The nitrate eating bacteria would fead off of the wood releasing CO2 Any oxygen loving bacteria getting in would consume the wood and most of the oxygen leading to the low oxygen levels needed for nitrate consumption to start.

95% of a plants dry mass is Carbon. Most of which comes from CO2. About 4% Is mostly nitrogen with smaller amounts of potassium, calcium, magnesium, phosphate, and sulfur ( commonly called macro nutrients.)The remaining 1% of the dry mass of the plant is the micro nutrients Chlorine, iron, manganese, boron, zinc, copper, molybdenum and nickel. Aquarium plants get the carbon they need from CO2 dissolved in water. plants get nitrogen from ammonia, urea, and nitrate from fish waiste. The rest of the nutrients they need come from the water column or substrate. If any one nutrient runs out plant will stop growing and will stop consuming ammonia, urea, nitrate and all other nutrients.

For animals and bacteria it is about the same. But there is one difference. animals and bacteria Get most of Carbon nitrogen and most of the minerals they need from what they eat. Bacteria feed primarily off of fish waiste and dead plant material and only use nitrate if oxygen levlels are low.

 

[glyn]

I've kept tropical tanks, freshwater and also marine, since 1977. I'm not surprised that the original poster's foam media has done so well. My experiences with different kinds of filter media over that time has convinced me that coarse, unclogged foam is pretty hot stuff.

OK, plastic media kept mobile, in suspension, with an air stone in a sump filter will probably do better, but in a canister filter that's impractical. As for all that ceramic stuff, pumice stone, Biohome, nobbly bits of this and that - well, they can't usually do much harm, but please don't pay over the odds for them.