Everyone can join the back of the queue on blame. The responsibility is all mine for the dimensional confusion. I hoped
w/h/d would be clear enough (not least as it was consistent with x/y/z axes) but was aware of the ambiguity of the
d. I wrestled with the idea of w/h/f2b but that seemed clumsy. Perhaps I should have gone with l/h/w. Oh well, what's done is done. I shall beat myself with a knotted rope this evening.
Anyway ... back to the plot ... loosely ...
@Wolf6 The gaps around my inlet/outlet pipes are pretty well sealed, as if they aren't, there seems to be enough evaporation that the marine-ply hood on the tank (which is integral to the light mounting) starts to warp ... despite around 6 or 7 coats of "waterproof" varnish.
The biggest problem currently is algae. I'm pretty sure that is at least in part due to circulation ... hence remaking the spraybars.
@Wookii My concern with angling the spraybars horizontally (as they currently are) is that there are areas at the bottom of the tank that don't get a lot of flow. I'm looking at increasing flow rate with better spraybar design (fewer, smaller holes): in such a tall, narrow tank, even a spray at 45
° still only represents a drop of 30% of the tanks height (where there are negligible plants) and might help with downward momentum. (Obviously fluid mechanics is not my area of expertise!)
Meanwhile the volume of "fresh" air at the surface is only about 3 litres, and only refreshed a couple of times a day at feeding time. I have no idea of the rate at which gaseous exchange takes place, so I don't know whether that's a limiting factor.
As for a half filled tank - it seemed to work as an ecosystem for quite a few years, and I like it as it is. But having had significant algae problems recently, I'm just trying to get back to where I was ... and reading myself down so many rabbit holes (flow / filtration / light / dissolved O₂ / etc) in the process.
@Hufsa I have run two canisters (with seperate spraybars) for a long time, but as part of addressing flow I have removed media from one, so it effectively acts as just a circulation pump. When I re-plumb the tank, hopefully the flow will improve further.
@dw1305 An interesting article on aeration. (I even understood some of it.
) Sadly, increased knowledge rarely seems to lead me to happiness. Now I learn that ...
As I live in a hard water area, the oxygen content of my tap water is likely to be lower. Such a pity I've been trying to do more water changes recently and run the rain-water butt dry.
On the upside, my heater died the other day, so my tank is around 4
°C cooler till payday.
For "airstone" location - all my hardware is under the tank, and I've got enough junk in the shed (and misguided DIY enthusiasm) to build an inline O₂ reactor (possibly a tubular EPDM diffuser in a 2" PVC tube.) I figure that's going to give a reasonable distribution, especially (if I understand
@dw1305 's article) if I site that before the canister filter, thus maximising the "residence time" and benefiting the nitrifying bacteria. (I'm hoping that wouldn't lead to a problem with airlocks in the filter?)