Filtration question. Problems occurring

[Askaleymanfish]

Not over stocked 2fx6 on a 125 is way more than enough filtration and I was having this problem with only 6 fish in my tank. It didn’t start until I loaded it with crushed lava rock. I no a guy on here who has just as many bichirs that r much bigger than man along with several other big fish in his 190 with only 1 fx6 running and he’s never had a issue. Filtration is more than enough. There is just a problem with it that I can’t put my finger on.

 

[duanes]

It does sound like the media could be too tightly packed, that instead of an aerobic environment, where normal beneficial bacteria thrive, that an anoxic environment has been created.
Cramming more and more media in a small space does not mean you get better bio filtration.
The population of beneficial bacteria is not determined by amount of media (as long as it sufficient), but will be limited by metabolism output of the fish in the tank, and aerobic condition created by flow.
If it were me, I'd remove some a little at a time (maybe a handful or two), and test the next day, to determine what is the a sufficient amount for the tank.
It may turn out half is "better" than a large amount


The chamber holding the bio-media in the sump above is only about 1 ft square, lots of interstitial space between chunks to allow unimpeded flow, and is sufficient for my 180 gal holding 15 fish mostly @ 5" in size.
The flow thru the sump creates this type flow and surface agitation in the tank.

The outflow of each pipe is 1", except the 2nd from the right 1/2", because of water lilies in its wake.
I also use lava rock, but I leave it in 1" to 2" chunks.

as you can see the flow allows for enough space to create aerobic conditions

 

[Askaleymanfish]

It does sound like the media could be too tightly packed, that instead of an aerobic environment, where normal beneficial bacteria thrive, that an anoxic environment has been created.
Cramming more and more media in a small space does not mean you get better bio filtration.
The population of beneficial bacteria is not determined by amount of media (as long as it sufficient), but will be limited by metabolism output of the fish in the tank, and aerobic condition created by flow.
If it were me, I'd remove some a little at a time (maybe a handful or two), and test the next day, to determine what is the a sufficient amount for the tank.
It may turn out half is "better" than a large amount
View attachment 1421198

The chamber holding the bio-media in the sump above is only about 1 ft square, lots of interstitial space between chunks to allow unimpeded flow, and is sufficient for my 180 gal holding 15 fish mostly @ 5" in size.
The flow thru the sump creates this type flow and surface agitation in the tank.
View attachment 1421199
The outflow of each pipe is 1", except the 2nd from the right 1/2", because of water lilies in its wake.
I also use lava rock, but I leave it in 1" to 2" chunks.

as you can see the flow allows for enough space to create aerobic conditions

Thank u yes my lava rock has a lot of smaller pieces than those packed in anywhere I could fit them in. Iv never been super great at filtration understanding. My thoughts were pack as much as I can possibly fit and i should never have a issue. Very wrong I was. I am goin to deal with the filters this weekend. I actually have a 3rd fx6 on a 225 that only has a 8” aro and two 3” fish in it and a 6” clown knife. And I hate ammonia in that tank. That’s when I knew it was the tank it was the filters cause that filter is set up exactly the same as the 2 on my 125 and there is no reason there should of been ammonia in the 225 with that small and few of fish.