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    everything fishy

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  1. Hi Ande, You right this looks like an old hydrotech. I had a couple of those installed at a farm I managed back in 1989 (I think).
  2. Hi Moses, fyi, T5 florescent are the most used lights in Indonesia. I wonder, why do you need artificial light while you on top of the equator? as this guaranties sufficient light the whole year. Going to be hard to beat the sun, and electricity is quite expensive in indo.
  3. Hi Moses, Which island; Nias or one of the Mentawi islands? I actually recently visited West-Sumatra and the Gramedia I mentioned was in Padang. Years ago I lived and worked in Padang so I do know Sumatra a little bit. Ande, I do think that Moses his first language isn't English (btw neither is mine) and that's why I advised him to check out local resources.
  4. Hi Moses, In which part of Indonesia are you living? Might be a good idea to check out your local Gramedia for books on aquaponics, I was in Indonesia last February and they carried some good books on the topic.
  5. Yes should be fine; rinsing with water, followed with a bit vinegar is all that's needed.
  6. Excellent find. This becomes more & more relevant.
  7. Hi, As a technical minded person active in the industry I am always interested in new technologies. Thus had a look what the Akva group has in their online add. While it might be good equipment there is nothing new here, uv; partial flow, full flow all has it's place in the aquaculture industry; I use both set-ups often at the same farm in different modules with different aims. Drum filters, again not new and or innovative at all. The new line of hydrotech drums has some interesting features, and seems to get away of rotation on demand, replacing it with slow steady rotation. As for European build RAS equipment, the best stuff is made here!! (me too but that's not related). If you can't find it you look at the wrong places, look in a aquaculture magazine and you will find lots of stuff. But don't understand me wrong, the fact that it's made there doesn't make it affordable. My favorite drum filter brand is Faivre (france) build like a tank, last forever but priced accordingly. btw I have a small faivre in my home system for more then 4 years and haven't touched it besides greasing bearings 2X a year and cleaning nozzles with the same frequency. As for Valodja, I mentioned this before, your plans are big and you seems to be inexperienced, please get a professional opinion before you commit to big spending's, and I don't try to sell myself here as nowadays I live in another part of the world. Another thing is is that on forums ideas move like waves of fashion, now it's sand beds or dual loop while before it was something else. Many configuration can and will work, if the operator has the skills, motivation, character and financial back-up (if it's commercial)....
  8. Thanks VKN, No it's not to late, I might try to run a feeding trial with snails for barramundi. So this are apple snails, which you grow on plants? Do you just feed some of these every day? any idea on impact?
  9. Hi Nate, This plastic is a thermoplastic; it will loose it's strength when the weather gets warmer. Thus if this deformation happened with cold or moderate temperatures you can expect it to collapse on a summer day.
  10. I consider a central bottom drain important for optimal water quality (much more so then the side drain). poop settling in a drain is a consequence of (too) low water velocity; you should increase flow or decrease drain/pipe size.
  11. This is a complicated system, especially the large elevation differences are going to demand several pumps for operation (at least if you want to operate these at a decent efficiency). You virtually always need a sump for smooth operation Pumps can be in-sump if you use submersible pumps, while other pumps need to installed dry; either with a flooded suction or above the sump level with a none return valve as most pumps are not self priming. Now I don't speak Croatian but numbers given on the drawing don't seem to match your statement;especially m2 plants vs fish tank volume As the money involved building this system is substantial it's best to have somebody with engineering experience look over your final design before you build it.
  12. If not zeolite probably Sodium Hydroxymethanesulfonate as main active ingredient. I used this for fry transport but never in a ras system for foodfish (residues??), thus can't help you here. btw zeolite would be safe in such an application.
  13. I am not sure this is accurate. As far as I know most ammonia removers are zeolite based, and they work mainly as ion-exchanger; thus NH4 (the ion) is bonded and another positive ion (often sodium) is released. This pushes the TAN equilibrium to the NH4 side and this lowers NH3 (the toxic stuff). btw if you would be able to absorb the NH3 only, due to small fraction of NH3, the ammonium dissociation equilibrium would form 'new' NH3 directly out of available NH4. Remember level of free NH3 is mainly determined by pH and TAN levels. To dive a bit further into chemistry, in general zeolite based products work far less efficient in hard water due to the high affinity of most zeolites for calcium, and you certainly have hard water. The API test kit is one with low accuracy at low TAN readings. I don't want to bag them and use them too (they ok for what they are), however I compared readings with a Merck spectrophotometer and found a discrepancy in low readings. To put it perspective the small Merck cost around $2000 + $1.50 per measurement. I have used ammonia removers in the past, mainly in transport-bags for fingerlings as putting close to 1000 small fish in a couple of litres of water for more then 12 hours easy courses ammonia problems.
  14. I am I missing something? Why don't you lower the pH? HCl for fish only systems works well. btw if you have pool strength dilute first, use googles and protection for yourself.....
  15. This is your fry system, which you feed 8 X a day? If so, don't worry, ammonia is produced all the time and broken down all the time. However nitrification rate depends (amount other things) on ammonia levels, thus if you don't remove the ammonia you filter probably will do this, and ammonia levels will stop rising. Something else is that some test kits are unreliable in the real low ranges, and TAN levels of 0.05 already give a color change comparable with 0.25. They tend to be ok for the higher range. With reference to TAN levels vs nitrification rates; for commercial systems I size biofilter on maximum allowable level of TAN (species specific) and the difference in size/flows and layout of such a filter is huge if the design point is a maximum of 0.5 mg/l compared to 2.0 mg/l. Obvious this translate itself in different installation and operation costs.