MiZuboov
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How much PO4 is high level?
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Tripod1404
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I wrote about this on an other forum years ago. In my opinion, the acceptable level of nitrate and phosphate is largely dependent on Alk, Ca and light levels.
Basically, higher nitrate and phosphate are, higher Alk, Ca and light should be (I would say above 9-10 dkH and 450 ppm Ca). Basically, corals can grow more soft tissue with higher nitrate and phosphate, and zooxanthellae can divide faster. To keep up with the carbon demand, corals (or more precisely zooxanthellae) would also need higher light intensity. If these are satisfied, to keep up with soft tissue and zooxanthellae growth, corals would need more Alk and Ca to build hard skeletons (especially since high phosphate inhibits calcification).
If nitrate and phosphate and Alk and Ca are low, soft coral tissue growth would be limited by available hard skeleton to support growth. This causes zooxanthellae to overgrow without more soft tissue to "take up" their growing population. Under moderate cases, you would get browned corals that you can see spiting out excess zooxanthellae. Under extreme cases, zooxanthellae stress the corals soo much that they will expel all of them and bleach.
I believe this explains why sensitivity to nitrate and phosphate is SPS>LPS>Softies. Basically, more dependent a corals soft tissue growth is on calcification, more sensitive it will be to the balance between nitrate, phosphate, alk, Ca and light. The higher end of this spectrum are SPS who cannot grow more soft tissue without more skeleton. LPS can grow soft tissue without more skeleton to some extend (by having larger polyps) and softies don't really have a skeleton to grow except for some calcified plates.
This relationship is also valid on the other end. In ULN tanks, alk and Ca needs to be low to prevent SPS tip burning. This is even true for sudden minor increases like alk and Ca increase from a water change . My hypothesis is that if alk and Ca are high, there is uncontrolled calcification the growing tips which basically causes the soft tissue at active growth sites to die, possibly due to the inability to keep up with a sudden increase in calcification. Keep in mind that SPS in ULN tanks are pale, especially at the tips, indication that they have a rather low population of zooxanthellae. So coral tissue at the tips are supported by the nutrients transported from the tissue below. As corals do not have a very effective nutrient transport system (mainly driven by concentration gradients an diffusion without no active circulatory system etc.), actively growing tips would run out of nutrients, starve and die if there is too much calcification.
Basically, higher nitrate and phosphate are, higher Alk, Ca and light should be (I would say above 9-10 dkH and 450 ppm Ca). Basically, corals can grow more soft tissue with higher nitrate and phosphate, and zooxanthellae can divide faster. To keep up with the carbon demand, corals (or more precisely zooxanthellae) would also need higher light intensity. If these are satisfied, to keep up with soft tissue and zooxanthellae growth, corals would need more Alk and Ca to build hard skeletons (especially since high phosphate inhibits calcification).
If nitrate and phosphate and Alk and Ca are low, soft coral tissue growth would be limited by available hard skeleton to support growth. This causes zooxanthellae to overgrow without more soft tissue to "take up" their growing population. Under moderate cases, you would get browned corals that you can see spiting out excess zooxanthellae. Under extreme cases, zooxanthellae stress the corals soo much that they will expel all of them and bleach.
I believe this explains why sensitivity to nitrate and phosphate is SPS>LPS>Softies. Basically, more dependent a corals soft tissue growth is on calcification, more sensitive it will be to the balance between nitrate, phosphate, alk, Ca and light. The higher end of this spectrum are SPS who cannot grow more soft tissue without more skeleton. LPS can grow soft tissue without more skeleton to some extend (by having larger polyps) and softies don't really have a skeleton to grow except for some calcified plates.
This relationship is also valid on the other end. In ULN tanks, alk and Ca needs to be low to prevent SPS tip burning. This is even true for sudden minor increases like alk and Ca increase from a water change . My hypothesis is that if alk and Ca are high, there is uncontrolled calcification the growing tips which basically causes the soft tissue at active growth sites to die, possibly due to the inability to keep up with a sudden increase in calcification. Keep in mind that SPS in ULN tanks are pale, especially at the tips, indication that they have a rather low population of zooxanthellae. So coral tissue at the tips are supported by the nutrients transported from the tissue below. As corals do not have a very effective nutrient transport system (mainly driven by concentration gradients an diffusion without no active circulatory system etc.), actively growing tips would run out of nutrients, starve and die if there is too much calcification.
iReefer12
Well-Known Member
The worst thing you can do is chase Po4 numbers with a technique/routine that you can’t stay consistent with.
IMO, GFO is such a pain in the butt to stay on top of and keep replacing. So you create these spikes when it exhausts and sudden drops when you replace it. It took me a year to realize that stability is more important than the perfect number. If you can change GFO religiously, then maybe that’s for you though.
I’ve recently started using Tropic Marin Elimi-phos rapid (basically Lanthanum Chloride) dosing it right into the top of the skimmer. It works pretty well to lower Po4.. and it’s so easy and maintenance free that I feel good about being able to keep it stable.
That being said, find what works for you, but the focus should be stability.
IMO, GFO is such a pain in the butt to stay on top of and keep replacing. So you create these spikes when it exhausts and sudden drops when you replace it. It took me a year to realize that stability is more important than the perfect number. If you can change GFO religiously, then maybe that’s for you though.
I’ve recently started using Tropic Marin Elimi-phos rapid (basically Lanthanum Chloride) dosing it right into the top of the skimmer. It works pretty well to lower Po4.. and it’s so easy and maintenance free that I feel good about being able to keep it stable.
That being said, find what works for you, but the focus should be stability.
Tripod1404
Community Member
Dissolved CO2. Mainly in the form of bicarbonate.
^this^
Right and left side of one of my tanks (screen shots from video) day of the video PO4 0.9, NO3 10, alk 8.4 calcium 435. Par is 300 on the bottom where the derasa is by the bubble coral. Getting 400+ par higher up. Tank gets fully saturated kalk through a doser. I dose 24/7 I don't monitor pH. I do 20g water changes every 7-14 days or when in think about it. Total volume is 220ish gallons. As long as I keep the ato and kalk reservoirs full it just cruises along. But that didn't happen over night. This is my oldest tank at 8 years. It's also my most succesful. I have 2 other tanks running. I used to have tons of hair algae covering the 3d background (left over from freshwater setup) I started manual removal but there were so many critters in the algae when I pulled it off I pretty much stopped and just let nature take its course.
iReefer12
Well-Known Member
Yeah, that’s why I resisted it for so long.. but I did research on dosing it directly into the top of the skimmer, it’s less effective but it “should” bind and then be removed in the skimmate… but it is something I’m keeping an eye on.
Tripod1404
Community Member
Yes, but it depends on the actual numbers, as well as the light intensity. LPS in general are less sensitive to alk and Ca levels since their soft tissue growth is less dependent on skeleton growth. For example Euphyllia corals can grow larger polyps that grow over their existing skeleton. Elegance coral is the extreme example of this, it can grow massively with minimal skeleton growth. But of course there is a limit, polyps will have a maximum size that they can achieve without having more skeleton. So an imbalance will eventually also stress them. The outcome can be browning, spiting out excess symbiotic algae, bleaching or tissue necrosis, depending on the species and the actual level of nutrients vs alk and Ca. IMO, one of the major causes of polyp bailout is nutrient/alk imbalance, where the polyp grows too large for its skeleton.
MiZuboov
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Now I have 15 No3, 0,7 Po4, 8 dKh 490 Ca.
Should I raise dKh or do any other adjustments? Or should I leave things as they currently are?
I do not know why calcium is so high, probably corals still consume it poorly.
Tripod1404
Community Member
I would not change it unless you have issues or have poor growth.
If you do increase it, make sure to do it very slowly like 1dkh a week and keep it at that level for at least month to assess any changes.
You Ca is definitely high, so I would also look into bringing it down to 450 or so. You may want to test your salt mix if it increased this much without dosing.
MiZuboov
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And yet I did not understand one point a little. you say that with high nitrates and phosphates, you need to keep higher levels of Alk and Ca. I would understand if you said that consumption is growing, but you said that it is necessary to keep higher rates. Do you think (do you know) why it is necessary to keep the higher values of Al and Ca? Or is it just to have a supply of these substances, because consumption is increasing?
And one more thing. You wrote that a greater intensity of lighting is needed to increase carbon consumption, did I understand correctly that without increasing light, corals cannot consume more carbon?
Tripod1404
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Corals can grow faster with higher N and P since that allows them to harbor a higher number of symbiotic algae. However, if Alk and Ca are comparably low, they will not be able to build more skeleton ( and consequently more soft tissue). This will cause symbiotic algae population to increase without an increase in the amount corals tissue. Remember that symbiotic algae live inside coral tissue, so if their number get too high, they will stress corals. This will cause corals to expel excess symbionts, and in extreme cases bleach completely. If N and P are high, you want to keep all and Ca high so that corals can keep up with symbiotic algae.
About light, symbiotic algae fix CO2. Like any photosynthetic organism the energy for this process comes from light. The exact nature of this gets into biochemistry and molecular biology, but in a simplified form, many components of light harvesting and carbon fixing apparatus plants and algae have is nitrogen and phosphate intensive. So with more N and P, they can increase their photosynthesic capacity and fix more CO2, as long as they are not limited by light. That is why you can give them more light.
Tripod1404
Community Member
Ultra low nutrient (ULN) systems. This mainly works for SPS corals, and is rather difficult to keep most LPS in such systems. Even for SPS, it is hard to say if the corals really healthy.
Good SPS colors achieved in these tanks is due to the low levels of zooxanthellae that reduce the brown color, and high levels of light absorbing/florescent proteins corals produce to quench excess light energy.
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