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- Nov 21, 2009
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Absolutely interesting. I need to test iron in my tank. You might have just answer my question. My p04 is at .57 due to dry rock leaching although with p04 this high and my mh's running 6hrs a day no algae film or any algae for that matter exist in my tank, there is some coralline growing on the rocks but that's it. I really need to look into this more.If you watch the video - you may be back at thinking that elimination of N and P is the way to go...Just remember high N and P didn't directly impacct the corals - they simply lead to elevated C which in turns feeds the bacteria and this kills the corals.
Growing algae or carbon dosing to lower N and P potentially exacerbates issues - particularly during a die off or sustained use. I'm not a fan of either of these methods as they address the problem by first assuming the wrong nutrients are in play.
There are High Nutrient Low Carbon (HNLC) reefs - these exist because thay are situated in open ocean, well away from land sources of iron.
Very very little iron is found in your water - but you add it with every feeding and it concentrates in organic complexes in your tank - deutritus - much in the same manner as phosphate. Algae holds reserves of iron - so again macros work against you.
Limit carbon, (DOCand POC) - to maintain control over your bacterial load. It doesn't matter what you N and P are - limit iron and you can't grow algae. No algae means low sugars, which means bacteria stays in regulation.
Your corals will get the iron they need from the food they capture.
Virtually any level of N and P seems ok. I've been doing this for a year now.
I can't speak for Robert, but I've had good success not worrying about PO4 (no fuge, no macro, no GFO), but always running Rox GAC (along with other carbon-limiting such as grazers, mechanical filtration and UV). Once my phosphate got above 0.25 (took almost a year), I did start getting algae, so I added some GFO at the recommended dosage. Although it did lower my PO4, my algae actually got worse, but it was a different strain that what had been building up previously. This new algae was decidedly more rust colored instead of green. The most logical conclusion is that my system was relatively iron-limited previously (due to GAC?) but the addition of GFO released enough iron that my system was no longer iron-limited and this allowed algae to flourish despite PO4 dropping.Well like I said earlier, I have been tinkering with the idea of getting rid of my macros for a while now. Do you think it best just to run ROX carbon and some gfo and leave it be?
Have you/Are you running GAC or UV? I have been avoiding algae with nitrates as high as 2.0 - 5.0 ppm and phosphates as high as 0.20 ppm, but I'm always running GAC and UV. Robert makes a strong case for why these carbon- & iron-limiting strategies are working for me even though I'm above traditional ULNS parameters.Ive tried dosing potassium nitrate as my system maintains a NO3 of O. That said whenever I dose the nitrate above 0.2-0.5ppm my algae wants to come out, which makes it to where I have to stop dosing. I swear I have Dino which only shows up when the NO3 are above .2-.5. Anyone have any advice on this one as I would like to have nitrates without the algae issue.