I started a thread on RC regarding the concept of phosphate "leeching" out of rock. http://www.reefcentral.com/forums/showthread.php?t=2309506 It was prompted by a discussion on algaescrubber.net http://algaescrubber.net/forums/sho...Hair-Algae-in-Display-Tank-with-Scrubber-Help I thought now was the time to bring this up, in particular (Ace you're going to love this) because of the claim made on this YouTube Video by Santa Monica Take it away, Ace. I know you want to rant on this one.
Well, the guys on RC seem to have the right idea.. Santa Monica on the other hand, not so much. To me, the sand bed is the most logical place for 'phosphates to leach from' in a system as it is very easy to create different 'zones' in a sand bed.. in a rock structure, not so much. Sure there will be tiny spots in rock formations that can create different 'ph zones' but I believe for the most part those zones are very tiny and almost inconsequential in the grand scheme of things. The chances of a rock structure being able to create a low pH zone down to the point of reaching the breaking point for phosphates to release are slim to none IMO. As others have stated, the amount of phosphates that release from rocks in a good working system is so tiny I would bet it doesn't even account for 1% of the phosphates in the water column, while food would account for 95% and the sand bed/detritus would account for the remaining 5%. As pointed out by the people on RC, bacteria plays a huge role in this topic. This is still an area were almost all of us are 'still in the dark' as I don't know anyone that regularly tests 'bacteria levels' on their tanks. What we do know is bacteria is able to 'eat up' excess nitrates and phosphates quicker than algae and get them to a lower level than algae is capable of doing (you see people over stripping their tanks quite often with biopellets, has anyone ever heard of over stripping a tank of nutrients using algae?). So if bacteria can do this more efficiently, the question becomes, what is feeding the algae on the rocks? Answer, look in the mirror. I fully admit that is and always been my problem, I feed way to much, and I know the #1 source of phosphates in an aquarium comes from food. So what is the answer? Obviously that differs tank to tank. I do think using products that are proven to work will help this issue, products like Dr. Tim's One and Only and Dr. Tim's Waste Away (bacteria). Second has to do with lighting. I do believe the majority of LED users (display LED) are lacking some important spectrums that greatly benefit bacteria. MH and T5 users do get those needed spectrums (400-420nm). That has been changing recently as people realize the importance of those spectrums, ie. 2 years ago you couldn't find a Mfg'd LED light that came with 420nm, new lights that come out today all seem to incorporate that spectrum. While I think the lighting Mfg's are looking more at the chlorophyll absorption when choosing those spectrums, a side benefit is it does aid in healthy bacteria populations as well. Lastly, responding to the video and comment... most of us know algae is not the best means of reducing phosphates from a tank, and quite a few of us have run into nitrate limitations in this regard. So to make a claim in a video that the algae is growing from 'the phosphates leaching from rocks' with zero proof of that happening is just stupid. A better video would have been showing phosphate test readings, not showing amount of algae harvested, because we know one does not necessarily correlate with the other. I can pull a pound of algae out of my system in a week, and in that time, phosphates will have gone UP, while nitrates will still read 0 on my test kits. On the flip side, I can remove my screen completely, use a couple bottles of good bacteria, and in that same time period I can see my phosphates drop in 1/2 in a week just from adding bacteria, or I can dose Lanthanum in a filter sock and bring my inorganic phosphates down to 0 and still get the same algae harvest than I got when phosphates were reading .50, which shows me that the algae is not relying on phosphates much at all.
Yeah, that's the stuff! As for the algae not relying on phosphates, I can't say I have the same experience. On the tank I have ran a scrubber on for the longest period of time, stand-alone, there is zero N and zero P, and it has been that way for almost a year now, ever since I switch from a 14x7 screen w/T5HO to a 4x6 screen w/LED (L2). While I can't say that the tank is 100% algae free, it certainly is not a major issue (loosely attached, siphons out easily, every 6-8 weeks I do a 1/2 hour tank cleaning). I guess we generally only hear from the people that are having problems. Most of the time, those problems are zero N and steady or rising P. To me, this is the #1 issue facing this device, and up until now, we only have explanations that very potentially completely baseless, which is quite frustrating. I stopped blindly trusting anyone on this and many other subjects a while back, and that is not limited to any one person. There are many "junk science" claims out there, or "this worked for me = will work for all" arguments...
SM may not be feeding his fish but they are still eating, one would presume. My Carribean Blue loves screen algae, the rest of my fish are not keen on it. Perhaps he has such a varied algae growth in his display that all the dietary needs are met. This must be where the phosphate is recycled. Back to the topic of phos leaching - in freshwater, algae produce enough organic acids to dissolve concrete and obtain nearly all required elements from the dissolved portion. Not found anything like that in relation to salty water though. http://www.scielo.br/pdf/mr/v12n4/v12n4a15.pdf
Wanted to make sure people saw this article. Goes hand in hand with what I saw saying above about bacteria being so important. http://www.advancedaquarist.com/blog/bacteria-provide-corals-with-much-needed-nitrogen
A couple interesting points have been brought up. The first is the concept of "bacterial cleaving", which is a process by which bacteria are able to create localized, low pH areas that may have the ability to access bound phosphate. Apparently this is in use in the medical field and I imagine it could have a use in farming but that's just a guess. The second is that algae, when starved for P, may release Alkaline Phosphatase in order to precipitate the release of P. These 2 mechanisms may be working with each other as well. It just seems that there is too much anecdotal evidence that something does indeed happen that causes algae to grow on the rocks until all the 'fuel' is gone, or at least, stabilized. There are too many instances of it happening. So once the 'why' is established, this may lead to a method to speed it up, perhaps by using both a bacterial source and an algae source of filtration. Which by the way does seem to work very well.
Ok, so this is the only part I can read. The rest is under login and in Chinese. So translate this into layman's terms?
Algae (the algae tested anyway) grows just as well in organic phosphates (which form a part of amino acids etc, and that we can't test for easily) as it does in inorganic phosphates (that we routinely test for). Considering folks are normally advised (not by us) to remove skimmers etc, could this be making it worse?
If you are saying that a scrubber (or algae in general) removes both Po and Pi, and the skimmer removes Po and the scrubber removes Pi, and you remove the skimmer, this might force the algae to adsorb whatever is most readily available or easiest to consume. That is if the situation is as I described. in this thread on The Reef Tank: http://www.thereeftank.com/forums/f218/macro-algae-vs-skimmers-213031.html#post2367864 It was brought up that algae is good a taking in Pi and producing Po: One would conclude that if such a mechanism does exist, then you would think that if you are running a skimmer with a scrubber that it would be producing more. But in most cases the skimmer produces less. With a few exceptions http://algaescrubber.net/forums/showthread.php?2766-Skimmer-functionality-when-running-a-scrubber http://algaescrubber.net/forums/sho...when-you-ran-with-and-witout-a-Skimmer-Thread! Just seems like the "study" information contradicts what actually happens. Why is that, and why does that seem to consistently be the case. The "studies" say X will lead to Y, but we don't always see that result.
Hmm - I've also read that algae filtered systems (caulerpa type refugiums) are on average 40% higher in organics than none algae types when run without a skimmer. All I can think of is the effect I saw on my waterfall. That is that after a while it seemed the screen utilises the organics for growth, which I understand is unbelievable, but it still nags at me.
What about non dissolved organics in the system - sludge, detritus, stuff down in the gravel or sand, stuff in the rocks, fish poop etc.? To me this stuff is a better candidate than rocks giving off phosphate. Everybody overfeeds their systems [my opinion] no matter how careful we are. An algae scrubber is great in that it can use up phosphate and Nitrate, but as you are saying, it is not the only thing to use for filtration.
