[Coral-List] NH4 additions and coral aquaculture
coralfarmguam at yahoo.com
Tue Jan 3 01:59:03 EST 2006
My name is Lee Goldman. I have been growing corals from larvae and planulae (that I collect and settle) for over three years now and I must admit that adding ammonia to the culture tanks was something I was very interested in. For my Masters Thesis, I had planned to test the addition of ammonia against the addition of artificial food and live food (Artemia spp.) with regards to coral growth. Unfortunately, my experimental design was very ambitious and my advisors (and my wife) wanted me to move it along and get back to living a real life so I changed my focus, but I digress.
I believe Julian Sprung was probably correct in assessing the reason for the initial question
to accelerate coral growth in aquaculture environments. My two cents is that it seems like a lot of work (ammonia additions) as well as fine-line walking in order to possibly achieve this. Heres why:
If the final concentration of ammonia in the given volume is in the order of 1-2 micromoles (as was suggested to me, and supported by other cora-listers in this discussion) then you would have to make up a stock solution of ammonia chloride (or nitrate but chloride may be easier since if your adding ammonia AND nitrate then your asking and getting a double does of nutrients that aquarists really dont want in their system. For research purposes following Nitrogen will also harder with two sources). Okay thats not too tough though, basic chemistry. Next, a given amount of the stock solution would then have to be added to the final volume of seawater (your tank volume) to give you a concentration of 1-2 micromoles. A few equations to deal with but not that intimidating, yet.
Now, the fun starts when you have to test the water for this. For most folks, its downright hard to test the water for ammonia at the micro-molar level, but you would have to in order to add more right? As any aquarist knows, you shouldnt add nutrients (or anything) into your system without knowing what it is going to do to your tank. The concern is the residual ammonia still in the system (especially if its a closed system). Adding your stock solution would add to the residual ammonia - increasing the total concentration in the tank. There are equations to handle adding a know solution into a volume of water with the said solution already present, but without knowing what you have (the initial concentration of solution) the equation will not help. Increasing ammonia could be detrimental to the corals and certainly beneficial to algae. More algae equal more work. Thats the fine line I was talking about.
There is an answer to this, and this is where the real work starts. You can simply drain your entire system and start over again (No residual ammonia to deal with). For my experiments, I was dealing with 300 ml vessels. Pour the cup out and titrate in the stock solution until the volume reaches 300 ml. Pretty simple. What if your tank is 300 L or 1000 L. Draining this system and filling it everyday would be work. And I mean drain it, not add water to displace the old water...you still wouldn't know for sure how much residual ammonia remains.
Furthermore, how quickly do corals uptake ammonia (or Nitrogen)? Even if you find a published rate is that true for your corals in your system? Maybe all of the ammonia (Nitrogen) is used very quickly. Maybe you need to does only a few times a week, maybe everyday but still, unless you know how much ammonia you have in your system and what the uptake rate is, it doesnt make sense to do it any LESS than everyday or your doing all to the above for nothing. Another point to consider is the other inhabitants in your tank. Do they uptake available Nitrogen as well? Charles Del Beek mentioned clam farmers using ammonia additions so we know other organisms can use it. (He also mentioned that clam shells tended to be more brittle which a cause for concern in the formation of the coral skeleton). Would the additions benefit just the corals? I suspect it would benefit all your tank inhabitants. This defeats the ammonia additions to some degree (competition for Nitrogen, for instance algae
would compete for Nitrogen, but not Artemia spp.). I suppose most coral farmers are keeping only corals in their culture tank, but is there a sand bed? Live rock? Biological filtration? This question of dwell time for ammonia also plays into those who would dose in an open system. How long do you close it off (so as to avoid having the ammonia chloride diluted or drained from the system too quickly )? If the corals take 12 hours to uptake (just saying), then do you close it off for this long?
I think there needs to be much more research in this area before it becomes a staple Nitrogen source for corals. Even then the amount of work involved would have to be justified by the increased growth rates of the corals (as well as the health of the corals due to the increased Nitrogen, which would also have to be measured in a scientific experiment) I am familiar with work on the Anemone fish and Anemone relationship and the transference of Nitrogen (in the form of waste) from the fish to the anemone, so it is not out of the realm of possibilities that Nitrogen (ammonia) additions COULD be beneficial to corals, however, that relationship does not require human intervention as would the corals nor does that relationship require an absolute and exact knowledge of added ammonia to the micro-molar level. Further corals may not have the same type of strong commencial relationships with fish (Pocilloporiids and Cirrhitidae, I hear ya, but your not as tight as the Anemone fish /
Anemone). As a coral farmer (who grows corals in both open and closed systems), I would be really concerned with the inadequacies in my understanding about what is really going on in my tanks with regards to ammonia and the benefits (or not) it has to my corals. If you really want to make corals grow faster in relation to published growth rates, do what anyone would do to foster the growth of any living organism
feed them more. Dealing with the increased food source in your tank would be much easier than the managing micro-molar concentrations of ammonia. The corals would not be lacking for a Nitrogen source with the availability of lots of food. I feed my corals a tremendous amount of Artemia spp. on a daily basis. In the closed system, I protein skim the heck out of my tanks and perform 20% water changes daily. In the open system, I close it off for about an hour and open it after that time to drain the waste. I get great growth rates and limited algal growth (although I
will not say that increased feeding is the only contributing factor to their growth), but most importantly, I am successful in rearing a large percentage of coral recruits into coral juveniles and then into adulthood. If, for arguments sake, the amount of work to dose ammonia in the system was equal to work for the increased feeding, wouldnt you still want to go with the feeding since it is easily more controllable (more variables that can be positively identified) and probably more practical?
three cents J. Sorry for the long winded observation.
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