A very informative article that says high phosphate level may not be problem by itself. http://www.reefs.com/magazine/15981...g-ix-test-kits-chasing-numbers-phosphate.html
Excellent article! Things are certainly changing w/r to how phosphate is viewed. Stability is the key and always has been, that has never changed. But freaking out about P levels might not be as necessary as once thought. I keep mine pretty stable, but in one tank, when the bioload increased a bit too much, I started to get rising P slowly over time and this knocked out a few corals. By the time I realized it, it was too late. Oh well the tank needs a fresh look.
Nice article. So, let's assume it's correct (using Liebigs law of the minimum) and in this case Iron may be the limiting factor (certainly not N and P in my system). This would suggest we shy away from feeding nori and supplementing iron if the tank has an algae problem, thus allowing the scrubber to remove as much iron as possible. And perhaps iron is even being devolved from GFO, as nobody seems to really know how iron (GFO) acts. This article suggests that the premise that scrubber removal of N & P is a growth limiting factor in display tanks, is wrong. It may in fact be Iron limiting growth after scrubber installation. Considering the amount of organic N & P which is continuously being cycled from organic to inorganic I can believe this, especially when factoring in the apparent low levels of iron in salt water.
Garf you raise some interesting points! Perhaps some experiments can be set up to test this. Are there any hobby test for iron?
The only one that I have used is Seachem. Their test kits are a bit of a pain though. They have these little white trays that hold very small amounts of sample water and they are hard to read correctly, so I would look elsewhere.
Could do with @Ace25 piping up. I know he has had the "phosphate ain't that bad" theory for a while. Let's see what other folks think http://www.reefcentral.com/forums/showthread.php?t=2028045
I don't think it is a theory when many reputable places have done studies and shown without a doubt phosphate levels under most circumstances, as long as they are stable, are not an issue. Of course there is an upper limit, but the vast majority of people would probably never hit that limit in even a badly designed system as long as there is some live rock and sand in the system for bacteria to colonize on. The only negative issue I see with high phosphates, but within reason (under 2.0), that occurs with stony corals is they actually grow TOO FAST, and when that happens their calcium skeleton suffers because it is growing so fast it can't create the same density in the skeleton, which makes them more brittle. For soft corals high phosphates should not be a concern, actually it should be helpful in making things like mushrooms, zoanthids, xenia, colt/kenya trees, etc grow faster, and my own observations have backed that. 2 tanks, 10 polyp frag of Sunny-D zoanthids, one in each tank. After 30 days, tank with phosphates in the 1.0 range doubled the amount of zoanthinds to 20, where as the system with low phosphates, under .05, I only got 1 new polyp in the same time frame. Obviously that is very unscientific as there are many other factors that could have played into the growth, but I do believe higher phosphates was the major contributor. As Floyd mentioned, STABILITY is the key in all aspects of a reef tank. Even with things like Calcium.. if you are running low numbers, 320 or so, and one day decide to bump it up to 'normal' levels, in the 420 range, really bad things can happen because the stability is now out of whack as the system tries to balance out the added Calcium with the existing alkalinity and magnesium. Slow and steady always wins the race in this hobby. I honestly believe keeping phosphates in the .5 - 1.0 range is the most ideal range for growth and health of corals, * as long as everything remains stable, can't stress that enough, stability above all else. http://www.advancedaquarist.com/blo...els-increase-growth-rate-in-acropora-muricata http://reefbuilders.com/2011/12/05/acropora-phosphate-growth/
So I have been seeing lots of posts on rc about having a little phosphate and nitrate for certain corals to thrive. But how could you achieve this with an ats when the ats will remove all phosphates and nitrates from the system?
It's my understanding, that with an ATS its not possible to drive the No3 & Po4 too low.. Think of algae as a lightbulb, and corals too just with a small battery. when you add curent(No3/po4) they both light up(grow) when you lack current the light go out in the algae, but not the coral its uses the battery reserve. There for the algae will never drob the No3/Po4 to absolut zero. i know this is overly simplified.
The algae on the ATS can only absorb as much No3 and &P04 as they can use, so if there is more than what they need most of it will remain in the water. That is if you feed more than what your ATS can process, there will be plenty for the corals and bacteria.
Actually, it is very possible to over-scrub. At our recent frag fest, one of our speakers was Charles Delbeek. He spoke about various forms of nutrient control, and mentioned Algae Scrubbers at several points during his presentation. After speaking with him afterwards, it seemed that he had no working knowledge or experience with "modern" techniques, only horizontal surge/style devices, so thta may be part of it. Most large-scale scrubbers were overly large in design. But in his presentation he did mention that some did find that the use of large algal turf scrubbers resulted in near total depletion of nitrate and phosphate, to the point where it was then theorized that the water was getting too clean. I will jump in and say that while that might be part of the puzzle, I do not think that is all of it. So much was not known even 10 years ago compared to now that drawing a conclusion that the water was too clean because of the scrubber seems like it can't be the case, given that some reefs in the open ocean have barely detectable nutrient levels, and this would be extremely difficult to obtain in a closed miniature system (in comparison). With modern scrubbers, which are as of a few years ago recommended to be sized per feeding, I do not think that N/P depletion becomes an issue honestly. You can oversize or over-drive a scrubber and perhaps run on the edge of ULN but nothing like what one would be able to achieve with say Zeovit, where you have to dose multiple chemicals just to keep everything above the bleeding edge of the blade.
Okay, I was under the understanding the the algae will stop growing and possibly die off if it gets neer zero
I don't think it will die off, surely. I have several tanks running at nitrates below hobby kit detectable levels and the algae keeps growing!
Sorry about my English I ment the algae would die off far before the corals. And surely there is still som no3/po4 still even if the test say zero.. You really believe an ATS can starve out corals before it starve out the algae?
I do not believe that algae can starve out corals by itself, that's not what I was saying, I was just saying that the scrubber keeps growing algae under low nutrient conditions. Tank algae should get out-competed
That i can agree on... But I am also an believer on a ATS can't starve out corals , like an skimmer can, as algae don't have "fat" reserve like corals.... Sure an overly oversize ATS will be able to out compeed the corals... But under normal operation it will keep the nutritions low and stable... If the nutritions drop to low the algae will slower growth until there is more... Sounds right or am I way off here?
Really the maintenance of SPS corals in particular is a bit more delicate than simply low or high nutrients, there are many factors to consider But certainly there are corals that under low levels of po4 and no3, fail, as there are others that under high levels if they do and the opposite In my particular case, the phosphate below 0.04 have several of my sps were seriously affected, as others nothing happened Now I try to keep my po4 stably above 0.04 and no3 above 0.5ppm And happy corals All this only with my ats and live rock regards
