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About Jonas

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    aquaponics in emerging markets
  1. Hi all, thanks for your numerous suggestions. After more careful examination it could look like Ich and the older Tilapia simply have developed a resistance... Anyways, I'll do the saltwater treatment as outlined in that post Ravnis referred to, thanks!
  2. Hi all, Water is crystal clear (1m depth), a handful of solids at the bottom can be seen at the bottom of the tank but really otherwise extremely clean. The gills look fine to me, the only unusual thing is the greenish spots from the pictures above. The fish generally seem quite happy and there still are some left, it's just that every day 1-2 fingerlings seem to go (the big ones are all happy). One thing I did notice today was that a few of the fingerlings had long thin poo lines hanging behind them for quite a long time (which looked very thin, almost chopped off at a few places), I remember once hearing something about fish poo dangling behind the fish for a long time as being a sign for something but can't remember (or seem to find) anymore what the explanation was. For the salt treatment, what kind of dosage would you suggest (e.g. how many grams/tbsp of salt per 1000l)? I don't mind risking the plants (transplanted some more mature ones which I'll just run as a separate hydro system for a few days anyways - thank god for thinking ahead with system splitting ability!) but would hate to lose the mature fish as they're the main bio mass in the system now anyways. Any recommendations? Thanks!
  3. Hi, We're starting a new aquaponics system (been running for almost 2 months now) and are having problems with fingerlings dying (1-2 every 1-2 days). The system has matured enough that a range of large fish have been living there comfortably now for the past 3 weeks (had some issues during cycling there but nothing since) and they're generally quite active and feed well. The water parameters all look healthy, Temp between 26-29 deg C (tropics! :-)), ph between 7.2 and 7.6, ammonia < 0.25, nitrite < 0.25, KH between 2-4 deg, sadly hardly any nitrates either but with a very low stocking density (about 15 larger fish for a 6m3 fish tank, 30m2 media bed system) that is not too surprising I guess and obviously shouldn't be causing problems with the fingerlings either. I have used the fingerling supplier multiple times before without any problems but this time it seems like we have something detrimental in the system. I'm attaching some pics which seem to show some kind of infection? Can somebody with more fish knowledge maybe help identify what the issue might be and what we can do to remedy the situation? Thanks!
  4. Are you close to that group? I am quite interested in the energy storage topic (including flywheels, hydro, compressed air etc.) - if you have any papers/research which looks close to market-ready I'd be very curious to see them. Interestingly, I just saw something that looks like this outside a university here in Yangon, a big compressed air silo hooked up to a generator for what seemed to be emergency power (as obviously outages are prevalent here) - the claim on the machine was 5.5 HP! My rationale was actually simpler - I'm more interested in oxygen (or rather aeration to be precise, obviously won't pump pure oxygen) than electricity anyways so there could be one (inefficient) step removed in this process. A quick look at diving equipment being sold on Alibaba for example shows that it should be possible to get a large bottle for <$100. These have about 15-18l @ 210bar so we're looking at roughly between 3,000 and 3,800l of air. So if I want to release this air over night (12h) where there is 0 light for solar generation, I'd be looking at a flow of 250 - 300+ L/h. Simple air pumps I have seen use roughly 1W/l airflow per hour, assuming some efficiency at scale, lets just say we need a 150W air pump to get 250-300l/h. If I do that for 12 hours, I need about a total of 1,8kWh. Now, assuming that air pump would run on 12V (not sure), that would mean I need a battery of 150Ah which would be fully discharged just to get the same total output (ignoring that full discharge obviously is very detrimental to life expectancy of battery). Such batteries go for more than $100 on Alibaba. Obviously, I would need to have a fairly serious air compressor to be able to fill the diving bottles in the first place but that's a different question (and looks like I probably have such a solution on hand anyways) - but could it be true that this kind of aeration backup is cheaper than the normal battery option (again as a disclaimer, I fear I'm at the dangerous stage of knowing a tiny bit about the topic but having massive blind spots, hence, might be missing something obvious here?)! One thing I still have to find/build/solve is the valve which in this case would slowly release the air in a controlled manner to ensure airflow for the actual 12 hours and not just release everything in one big swoosh within a few minutes. Hydro was interesting as well, If scaling up though the structural requirements get quite significant to hold multiple tons of water high up in the air by consequence again increasing costs quite significantly... Very interesting comment on the difficulty to fix such things - makes perfect sense that this is a risk and something to keep in mind, don't want Murphy to succeed too often ;-)
  5. Great points (especially the "obvious" solution of using an air breather - commercially though unfortunately not quite as attractive here...) Not sure I understand your last sentence though - do you mean that it would probably be cheaper to oversize the battery and just run a low power air compressor off that battery?
  6. Hey Yahoo2, excellent, looks like the kind of simple sheet required - unfortunately I can't really comment on whether it's realistic or not as I'm at a similar place to you but hopefully somebody else can! :-p
  7. Hi all, I'm currently preparing setting up a fairly serious sized system in Myanmar, obviously a place struggling for decent power which needs to be keptin mind. Naturally, I'm worried about aeration, especially during nights (during day time fortunately solar should provide good energy even though obviously sun intensity varies throughout the days). Whilst toying around with the classic solar panel/battery solution for aeration, I was, mainly from an intellectual stimulating point of view looking at various other energy storage options (flywheels, alternate batteries, pumped storage hydroelectricity etc.) to come up with something with high levels of resilience at low cost. I do not know too much about this area though so currently this is pretty much just an abstract, theoretical thought experiment with solar/battery being fallback option. However, one thing I was wondering was if it might be possible to directly use an air compressor which very slowly releases air directly into the fish tanks at night if power goes down ("leaking" air over a 12h period or so)? Again, I'm not sure if such equipment exists, if efficiencies even remotely make sense etc. but would it be possible to compress air into an extra air cylinder during daytime and then when power goes down during night slowly have that air released from the unit into fish tanks through simple airstones? Thoughts? Thanks, Jonas
  8. Essentially things increase proportional starting from a base of 1/2" = 150 gal/h at 2" drop, right? I need larger flow rate, hence, am looking at 3" piping so for horizontal flow that would mean 3,375 gal/h flow rate and for vertical 5400 gal/h with min drop height of 81" - can anybody confirm? Also, does anybody know a good rule of thumb for how the vertical flow rate declines with reduction of height? (i.e. would it be only half at 40.5" [which I don't assume] or a quarter, eighth?) Thanks!