Mbuna flow requirements
In general, most sites say the you need 4-8 times your tank's volume to provide enough flow to keep your tank healthy. But I can't find anything that talks about how flow requirements differ based on what type of filter you're using. It seems logical that if you have a trickle filter (Jebo style), the flow requirements would be much lower than a power filter, since the trickle provides so much more aeriation and has much more area to put bio-media and carbon.
I have a huge trickle filter, but the flow is only around 2x my volume, which is stressing me out a little. I was told that I shouldn't worry about it because I'm getting much more aeriation with a 2x trickle filter than one would get with an 8x power filter, such as an AC or penguin, because the trickle sprays the water over such a large wet-dry area. For now, all my water parameters are flawless, but will this be a problem as my 15 mbuna grow to adult size? I was told that with 50% a week water changes, I'll be fine without getting a second filter. I want to believe this is true, but I'm looking for some other opinions.
The main question: how much less flow do you need when you're using a filter that gives you so much more aeriation and bio-filtration per volume? Because the sponges take up so much space on top of my tank, my only option for a second filter would be an under-gravel, which would be a pain in the rear to install since I'd have to remove all the gravel; so I'm praying that the trickle action will be enough over the long run.
Who thinks I'm doomed if I don't get a second filter?
Two mbuna tanks (a 180G and a 75G).