Filtration for 12ftx5ft blackwater aquarium question

[anewbie]

I'm planning a 12ftx5ftx18 inch blackwater dwarf cicihld aquarium. My initial thought is as follows:
i will inject some amount of water - i'm guessing 10gph on bottom of the right side and then have a pair of holes at the top of the left side for drainage - so the water will flow from left to right at approx 10gph (not sure if that is enough flow); the population will be two or three species of dwarf cichild - depending on availablity and feedback on aggression for a tank of this size - right now my thought is d39, nijjensi and laetacara dors with approx 200 to 300 dithers such as n. maryilyn, morse code tetra, ruby tetra and similar 1/2 inch to 1 inch size critters with 3 to 8 whiptails of various species such as Sturisomatichthys aureus or Loricaria simillima; probably 4 of 2 species and some number of otto - maybe 20.
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The target temp will be between 74 and 78 depending on precise dwarf cichild with ph 4.9 to 5.5 and ec around 25 to 35.

The open question is do i need more flow, more filtration (the above description excludes a sump though i will put in several - maybe 3 or 4 sponge filters in the back), and is 10gph a good value for water change over.
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I've not been to the amazon tributaries where these dwarf cichild are caught but they are generally described as having 'low' flow but one person low flow might be another fast flow so it is a nebulous description.

comments ? feedback ? Please serious reponses or serious questions not ad-hoc comments.

 

[GaryE]

I haven't fished in Amazonia, but my impressions from video, and from seeing lots of tributary, smaller rivers here and in Africa is that streams behave more or less the same everywhere. Larger rivers can be slow and lazy, but streams move. And slow rivers have strong undercurrents, as do lakes.

I've always read my beloved African killies come from slow streams, but it would be technically challenging to make aquarium water move as quickly as we encountered without having circular tanks. The streams had surface agitation and strong currents, moving through at many times an aquarium's volume many times an hour. I know that's vague, but even the shallow dwarf Cichlid streams had riffles along them quite regularly.

It completely changed my sense of fast and slow flow, and really made me rethink how I keep my fish. That fine line between flow and turbulence is easily crossed in our rectangular tanks where water hits walls.

Have you ever combined slender bodied Apistogramma with chunkier ones? I always kept species one to a tank, and have never considered how they interact.

 

[anewbie]

Have you ever combined slender bodied Apistogramma with chunkier ones? I always kept species one to a tank, and have never considered how they interact.

Most of my tanks are species only - i do have wavarni with a. norbert in a 100 (48x30) and at first the female norbert objected but after a week they started just ignoring them - they have been together for approx 4 months.

In my 500 i had blue rams with laetacara dors and they never interacted. the tank was a bit warm for the laetacara at around 78 but they are still alive 2 years later.
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In a 65 i have laetacara dors (wc) with a. sp d39 and it seems to mostly work but hte d39 are a fairly docile species. The dors come up front during feed time but otherwise stay in the very back - the d39 seem to have two territories about 8x12 sqft on both ends with the rest of the tank free roaming area.
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This aquarium is huge at 12ft x 5ft so it is hard to judge how the fishes will behave compared to putting them in a 20 long or 29. The a. nijjensi are said to be quite territorial but the number i've seen people quote is 3qft for territory which this aquarium can handle.
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Still the open question is if i need a sump or if the water turn over will provide sufficient filtetration.