Hi Sahin,
I see that you and many other reefers recommend not to run too much GFO to strip water out of too much phosphate. I don't know too much about chemistry so this really confused me. If you don't use GFO to export Phosphate, then where does all the Phosphate go? Our system is a closed system. What goes in must be consumed or export out. So if you don't use GFO, then Phosphate got consumed by corals, algae, bacteria? or got bind into the rock and will be release later day when they are full? I can understand that the rate of consumption of Nitrate is much more than Phosphate like 16 to 1 or something (just a general number), so we don't worry much about Nitrate. But Phosphate is different, not a lot of organism consume them, Algae doesn't take a lot of it. So with all the people that recommend not running GFO, then how do you control phosphate? Changing water, vacuuming the sand bed help but it is nothing compare to a cup of GFO when it comes to exporting Phosphate.
Thanks,
Good subject. The answer I have for you is just my experience. And the experience of other SPS keepers with great tanks/nicely coloured acros.
I present a couple of threads:
First thread is an example of a basic system; no GFO usage. Ed's PO4 level used to be something crazy like 0.25ppm (or higher, checkout the thread). But his coral colours are pretty damn good. His PO4 level is still probably higher than what is in most tanks.
http://www.reefcentral.com/forums/showthread.php?t=2197142
This thread contains some VERY beautiful tanks; with great colours in the SPS and NO GFO usage (some tanks even have high PO4 levels).
http://www.reefcentral.com/forums/showthread.php?t=2289842&highlight=gfo+free
Note member Rbtm's setup and the PO4 level (0.18ppm). That is Adam at BattleCorals. His SPS corals as you may know are VERY nicely coloured. This guy sells SPS for a living. Its in his best interest to use GFO if he thought it would be good for his corals which means more coral sales. But he doesnt. Because he doesnt need to. He has long worked out that GFO has been heavily hyped by the manufacturers.
There are MANY other build threads you can find on this forum; they have great SPS colours and dont run GFO. Of course there are tanks with just as nice colours that use GFO as well. But I believe GFO is not a constant requirement. And the ones that do use GFO, most likely feed the tank well etc.
I have seen with my own eyes, my buddys tank before he took it down due to a house move and lack of funds at the time: it was a basic system with a refugium and DIY LED/T5. His PO4 level when I first saw his tank was around 0.08ppm (measured with my Hanna ULR Phosphorus meter (when I had good reagents), and measured with his high end Merck Phosphate test kit). Even at 0.08ppm, he had great colours.
However, when I saw his tank some months later; his PO4 had risen to 0.25ppm...the colours in his SSC was AMAZING! The colours in his SPS were the deepest and best I've ever seen. In any tank. Now, I am not saying that the high phosphate was responsible for the amazing colours.
What I am trying to convey to you is that the high PO4 level didnt make his acros turn brown. In the presence of what most consider very high phosphate level, his SPS colours were great!
Since Phosphate removers became mainstream, there have been SO many threads about pale colours/lack of colours/other issues. Go through the SPS forum and see for yourself.
The combined effect of PO4 removers/GAC/highly efficient skimmers and other forms of filtration are so efficient these days that IMO we easily tend to cross the line and have a tank devoid of nutrients and other useful substances/materials that our corals require.
GFO removes way more things out the water than just Phosphate:
http://www.reefkeeping.com/issues/2004-11/rhf/ We dont really know to what extent the GFO binds other compounds/elements. Nor are we really sure of what the effect of GFO having removed these compounds has on our corals. Pale corals? Lack of colours? :uhoh3: Light brown coloured SPS?
GFO is a tool. It shouldn't need to be used permanently or in very high amounts. I used it at the start to reduce the PO4 level in my tank in an effort to control algae growth. Now that the level is controlled by my filtration system, I dont need to use it. Should my PO4 level start to get closer to 0.1ppm I will chuck some GFO in.
Where is it going in my tank? I can only guess that the amount of PO4 going in is being taken out by water changes/skimming/bacteria using it up and being skimmed out/being bound up into coral tissue/being bound to the substrate/being taken up by the algae in my refugium. I was also dosing Prodibio, but stopped both the GFO and Prodibio when I noticed my glass wouldnt need cleaning for nearly 2 weeks...I knew I had hit very low nutrient levels and my corals didnt look their best at this point.
Anyway, if lots of PO4 is being bound up in the substrate, then at a certain point, the substrate will reach a point where it cannot bind any more. At this point the levels of PO4 in the tank will surely rise. At that point some GFO can be used to reduce the levels.
Or I can replace part or section of the sandbed. I only have minimal sand in my tank. Its only 1inch high; so not at all difficult.
I currently have the following fish:
1x Tomoni Tang
1x Regal Tang (he is not suitable for my tank I know...but he is quite small and I intend to upgrade next year, if I dont, I will send him to my buddy with a 250G tank).
1x Fairy Wrasse
1x Yellow Wrasse (dont know its name).
In the next few months I will add a few smaller fish.
I threw my Hanna ULR Phosphorus meter in the cupboard. I no longer feel the need to try and achieve ultra low levels. I look at my corals and tank; they tell me whats happening with nutrient levels.
The colours in the SPS will come from feeding the tank well, keeping parameters stable and carrying out regular water changes (which removes harmful components and maintain trace elements), good flow and good light.
What do you do to keep your phosphates so low?
I used GFO/GAC/Prodibio in the first 4-5 months to control phosphate.
Tank manages PO4 and NO3 at these levels:
PO4=0.02ppm
NO3=0.2ppm
I dosed Nitrates many weeks back to raise nitrates to 5ppm. I didnt see any improvement in colours. The system bounced back to its 0.02/0.2 levels soon after.