As I've been busy with the rest of life, the time has been quickly eaten-up, but a few more thoughts on bio-pellets are due.
I mentioned in the last up-date, the PO4 level was slowly rising, while the NO3 was stabile at about 0.25ppm, which is extremely low. These readings were taken with the new Red Sea test kits, which I have been playing with and do seem to be accurate. In short, over the last 3 weeks the PO4 has risen to about 0.3ppm, which is extremely high for ULNS (actually right out the top!). Although I had suspected my skimmer may have been less than efficient, I have taken time to re-clean it and play with its setting to maximize efficiency and am satisfied it is doing its job. Then why the strong rise in PO4. Well, it would seem we have a classic example of nitrogen limitation, which is throwing the Redfield ratios through the grinder. With only a scant amount of nitrogen available, the bacteria are unable to assimilate the PO4 efficiently. We have been supplementing carbon via the pellets, and they are doing a fab job of reducing the nutrients, but, at some point, if there is not enough nitrogen available for PO4 reduction, the levels will simply rise. Solution: add nitrogen to system.
I have started adding enough ammonia to the tank to raise the levels of NO3 to 4ppm. Testing the water after 2 days showed that the NO3 had reduced to 2ppm and the PO4 was down to less than 0.2ppm, which seems to show that this is working. The next reading (24 hours later) was a PO4 of 0.15 and the NO3 has dropped to 1ppm or a bit less. I will continue dosing the ammonia and see how low I can get the PO4.
What I had found interesting during this PO4 rise, with the extremely low NO3 was, the corals did not brown out. Rather a few became lighter, which leads me to believe that the NO3 is the main food for the zooxanthellae, not the PO4. On the other hand, polyp extension became less and finally stopped altogether as the PO4 rose. Also, growth slowed considerably, especially in the acroporas. It would seem clear that the PO4 is interupting certain processes. It has been documented that phosphorus ions will be built into the aragonite matrix of coral sleletons, should it be in overabundance, to the detriment of the structure. It has been mentioned in research that the phosphorus ions prohibit the addition of Ca+ and Mg+ to the structure, causing a slow down, possibly impass, in the construction of the skeleton.
I mentioned in the last up-date, the PO4 level was slowly rising, while the NO3 was stabile at about 0.25ppm, which is extremely low. These readings were taken with the new Red Sea test kits, which I have been playing with and do seem to be accurate. In short, over the last 3 weeks the PO4 has risen to about 0.3ppm, which is extremely high for ULNS (actually right out the top!). Although I had suspected my skimmer may have been less than efficient, I have taken time to re-clean it and play with its setting to maximize efficiency and am satisfied it is doing its job. Then why the strong rise in PO4. Well, it would seem we have a classic example of nitrogen limitation, which is throwing the Redfield ratios through the grinder. With only a scant amount of nitrogen available, the bacteria are unable to assimilate the PO4 efficiently. We have been supplementing carbon via the pellets, and they are doing a fab job of reducing the nutrients, but, at some point, if there is not enough nitrogen available for PO4 reduction, the levels will simply rise. Solution: add nitrogen to system.
I have started adding enough ammonia to the tank to raise the levels of NO3 to 4ppm. Testing the water after 2 days showed that the NO3 had reduced to 2ppm and the PO4 was down to less than 0.2ppm, which seems to show that this is working. The next reading (24 hours later) was a PO4 of 0.15 and the NO3 has dropped to 1ppm or a bit less. I will continue dosing the ammonia and see how low I can get the PO4.
What I had found interesting during this PO4 rise, with the extremely low NO3 was, the corals did not brown out. Rather a few became lighter, which leads me to believe that the NO3 is the main food for the zooxanthellae, not the PO4. On the other hand, polyp extension became less and finally stopped altogether as the PO4 rose. Also, growth slowed considerably, especially in the acroporas. It would seem clear that the PO4 is interupting certain processes. It has been documented that phosphorus ions will be built into the aragonite matrix of coral sleletons, should it be in overabundance, to the detriment of the structure. It has been mentioned in research that the phosphorus ions prohibit the addition of Ca+ and Mg+ to the structure, causing a slow down, possibly impass, in the construction of the skeleton.
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