Phosphate that won't go away

[ferdinand]

some using potas to catch fish hiding in corals

[ferdinand]

I dont have a hanna checker but with other tests my phosphate is always zero with the waterfall scrubber tank, I only have detectable phos in my UAS 150G tank, my 10G UAS scrubber tank also measures zero.

150G is a lot, i don't think UAS can handle it in instant, especially when you keep feeding.

What it good about nature, they only take what they need, not like human that can take more than their capability.

well if SM not wrong, algae pop in the sea is 90% of sea itself, so how much pop of algae in our aquarium?

[SantaMonica]

So maintaining pH at the higher maximum precipitation rate of 8.4 ish (optimal for calcification) should limit or stop phosphate/carbonate dissolving, hence stop this leaching given adequate circulation.

Have not thought about how the equilibrium would work for quite a while. Sounds plausible. Very high pH (9+) will start precipitating P directly.

It's a potassium limitation

Introduced by food, although so is N and P. Personally I dose ESV Potassium Iodide.

what cause those phosphate anyway? from the food we gave?

Yes, all nutrients come from the food you feed.

algae pop[ulation] in the sea is 90% of sea itself, so how much pop[ulation] of algae in our aquarium?

That's a very good question. Algae is 90 percent of all biomass (except bacteria) in the ocean. I doubt we have 90 percent algae biomass in our tanks, compared to the fish, inverts and corals.

coupled with the fact most tanks contain more methods of nitrate removal than phosphate leads to higher than desired phosphate levels over time in most tanks.

Not true. Algae adjust their N/P assimilation ratios to absorb more P when it is available. As does cyano.

my phosphate is always zero with the waterfall scrubber tank

A good example. If P "built up", this zero test would be impossible.

So now, I think I have figured out how to explain what is happeing, especially with regards to P tests this year (at least on this site). It's hard to explain invisible things, like when you try to explain the nitrogen cycle to someone who has never had an aquarium. Or explaining voltage and current to someone who has never connected a wire. But at least those things can be measured/tested, so people who know what to look for can get the data they need to show you how things work.

Phosphate flux is different. Our tools/tests cannot measure P flux, only standing P amounts. A standing amount of P is like a voltage, or a bucket of water. A flux of P is like current, or a flow of water.

What is happening is that rock (and to a lessor extend, sand) acts like a capacitor, or sponge, or leaky bucket. When a new tank is set up with fresh rock and no live stock, P in the rocks equals P in the water, which is zero. Feeding the tank will instantly put P into the water, which is like turning up the voltage, or pouring water on the sponge, or putting water in the leaky bucket. If you pour a bunch of liquid food in, you will be able to instantly measure P in the water. But you can't measure the flux (flow) of P into the rock.

How fast does the P flow into the rock? Just like voltage and current, the bigger the difference between the P in he rocks and the P in the water, the bigger the flow of P will be into the rock. This is the same as applying a higher voltage across a capacitor, or spraying more water onto a sponge, or pour water faster into a leaky bucket.

So, in this example of a new tank that you just started feeding, if you fed 10 times the amount of food, P would flow into the rocks 10 times as fast. Can you see this flow? No. Can you measure it? No. But it's flowing very quickly into the rocks which are acting like an empty capacitor, empty sponge, or empty bucket.

Well as we know, the rocks eventually "fill up" with P. This is the typical time that rocks start growing algae on the rock, because the rocks are no longer pulling P inside; thus the P is available at the surface of the rock to grow algae. In a tank without good P filtering (like a scrubber or carbon dosing), the P levels in the water stay pretty high, pretty much in equilibrium with the rocks. This is the same as the voltage differential across a capacitor now being zero, or the water being sprayed onto a sponge being the same amount of water in the sponge, or the water in the leaky bucket having risen up to the top and spilling out as fast as new water is poured in. So in this situation, what is the P flux? It is zero. Even though P levels are high.

Now, you install your scrubber, or other P remover. P levels in the water immediately start dropping. This is what you measure; P levels in the water. This is all you can measure. You can't measure P levels in rocks, and you can't measure P flux. So you keep reducing the P levels in the water, and your tests keep showing less P. Great. This is just like bleeding the charge off of a capacitor (with a resistor, etc), or reducing spray onto the sponge, or reducing the input into the the leaky bucket. All of these things cause more to come out than is going in.

So how fast is P coming out of the rocks? Just like a capacitor, it is proportional to the difference of P in the rock, and P in the water. So if your P filter (scrubber, etc) is very strong, the P differential will be very great, and the P flux out of the rock will be very high. If you could multiply the power of your scrubber times 10, and all of a sudden it could absorb P ten times as fast, would you be able to measure this with your test? No. Not right away. The P would be surging out of the rock 10 times faster, just like the current would be flowing 10 times faster out of the capacitor, or water out of the sponge, or water out of the bucket. But you would not test a difference until the levels had time to change.

Another example: If your P measured 1.0 at 10am this morning, and at that moment you hooked up several buckets of GFO, at 10:01 the P would still measure 1.0 even though the P would be flowing very very quickly into the GFO. Maybe at 10:30 you would measure 0.9, but the idea is that the very instant you applied the GFO is the instant with the greatest flux of P, but no measureable change in P.

So with many people using scrubbers, P levels dropped, and P came out of the rocks, and stayed low enough to not be a problem. But how much P came out, and how fast? Well for the first few years, few people had green screens, and nobody had 3D growth, so filtering was weak. Thus, the flux of P out of the rocks was slow. It did evenually reach "zero" for many people; the less they fed, the quicker it could get down to zero. But of course with each feeding, or each scrubber cleaning, P would go back up a bit. P is of course never really zero anywere, but as long as the fluxuations were small relative to the levels, the tests would show zero. This is an important point.

Stated another way: As long as the relative levels of P in the rocks was not too low, then the slight variations of P in the water would not cause too much flux. This is like not applying too much voltage differential across a capacitor, or not changing how much water you spray on the sponge too much, or not changing how much water you pour in the bucket too much. As long as the levels stay about the same, the flux will be minimal.

But what if you drastially change the levels? Even if the levels are very low, if you quickly change one even a little, then you get a fast surge. If you have 0.1 volts on each side of a capacitor and then increase one side to 0.15, there is going to be a large current surge (with no resistance). If you turn a firehose on to your sponge or bucket, water is going to flow into it VERY fast even if for a short time. This is what feeding does. Feeding puts a surge of nutrinets into the water, both instantly/directly from the food, and almost instantly/indirectly from urine and waste. So within a few minutes the water now has a (relatively) very high level of P compared to a few minutes ago.

This feeding causes a HUGE flux of P into the the rocks, because the levels in the rock were so low. The levels in the rock would still be "zero" if you could test them, however, because the flux does not last long enough to raise the P in the rocks much.

How does this tie together? Scrubbers became more powerful this year due to reduced screen sizes (allowing more 3D), LEDs, and better knowledge of operating them. And people (especially scrubber people) are trying to feed more and more. This would probably apply even more to the people on this site. So as the scrubbing got stronger and stronger, even when the P levels were low, feeding input got higher. Thus, the flux of P is greater now then ever.

So, after a feeding, the stronger scrubbers would cause a HUGE flux of P out of the rock, even though the amount of P is low. The flux does not have to last for long, but it's like a shorted capacitor, or a firehose on the sponge or bucket. It could also be thought of like a water squirt gun: a tiny amount, blasted real fast. If you are in the way of the squirt gun, it will have a big effect on you, even though the amount of water is less that you would drink.

It can also be though of like this: If you have a sponge packed with water, and you completely stop spraying it, it's going to start dripping rapidly. If you have a leaky bucket and stop putting water into it, it's going to rapidly leak out. And with tanks, if you have low P levels in the rocks and the water, and you quckly reduce the P in the water even further, you are going to get a QUICK SURGE out of the rocks, as the P races to the scrubber. It could also be thought of like a shallow pan of water; the water could be only 1/16 inch deep, but if you tilt the pan you will get a quick rush of water for a brief second, enough to splash your face and fill up a cup.

Now, the "quick" flux of P into and out of the rocks is not for just a half second, of course, it's probably for several hours. But hours are a short time relative to the months of nutrient reductions techniques. So when this P is fluxing either into or out of the rocks, your tests are picking it up.

Solution? Have not thought about it much. I'm sure that more constant feeding, and more constant filtering, would help. Of course there will always be some tanks that really do have skewed N/P, at least for a while. But the more you feed, the faster this should even out, due to the adjustable N/P assimilation ratio of the algae. However the fact that many people have no excess P, or actually have excess N, does not lend a lot of weight to the accumulation of P theory, since the same chemical process would have to apply to everyone. Even what I say here is theory since I can't measure it.

The reason that the "planks in the bucket" are different, is that in the ocean there is no changing P flux. P is in constant flux, not transient, within the microbial loop. There is no giant rock nearby, absorbing P and releasing P. Almost all water is isolated and surrounded by just more water. If you want to compare to the "planks in the bucket", you would have to raise and lower the P plank with each feeding and filtering.

[Floyd R Turbo]

I can partially agree with your explanation, however it does still leave me with questions:

1) this still does not explain Ace's bare-bottom, no rock frag tank with rising P
2) I would like to understand the specific mechanism of how P is absorbed and leeched from rocks.
3) excessive feeding should also lead to rising N
4) The "planks in the bucket" concept applies more to our tanks, as levels are not constant, and therefore a strong variation (limitation) of one of them affects the nutrient cycle to a higher degree.
5) not everyone is overfeeding their scrubbers (in fact, I am under-feeding, and have been for a while)

I have been wondering about #2 for quite a while actually and until just recently I have not seen (nor really searched for) a true scientific explanation of this mechanism. The relationship to pH was the closest things I could see to an explanation thus far.

[Ace25]

I can partially agree with your explanation, however it does still leave me with questions:

1) this still does not explain Ace's bare-bottom, no rock frag tank with rising P
2) I would like to understand the specific mechanism of how P is absorbed and leeched from rocks.

I have been wondering about #2 for quite a while actually and until just recently I have not seen (nor really searched for) a true scientific explanation of this mechanism. The relationship to pH was the closest things I could see to an explanation thus far.

Part one I have my own theories on which doesn't quite relate to this topic (had more to due with algae/adaption and my specific experiment). Part 2, here is a quote from another site. Bottom line, 2 methods phosphates can leach out from rock, either from ultra low pH (below 7.0) or clogged with detritus which would mean you either have insufficient flow and/or cleanup crew/bacteria.

http://www.nano-reef.com/forums/inde...owtopic=265251

from a chemistry standpoint phosphates are bound up to another ion (they dont exist in your rock as phosphate, but as say calcium phosphate, magnesium phosphate and sodium phosphate) in order to have phosphates in your water come from these sources you would need to exceed the breaking energy of these bonds. bacteria do this much more efficiently when they break up food, fish poo etc. are your rocks releasing some phosphate ions? sure, but they might account for .001% of your total phosphate concentration.

I will fully admit that crap might clog the pores and then "leach" stuff back out. But not actual bound phosphates that have incorporated themselves into the actual chemical structure of the rock. Crap floating out of a rock is a different story than a rinsed/cleaned rock that is "leaching" simply because it went from a high phos to low phos environment.

[srusso]

True, and with Brightwell your concern is valid. Brightwell is probably my least favorite company in terms of supplements, they over exaggerate or flat out lie about some of their products, but some of their products are simply a known ingredient or mixture and water and listed on the bottle, which is the case here. I am sure I overpaid 1000 percent vs if I could just find the raw ingredients and mix them myself. Not too many places seem to carry the Salifert Potassium test kit in the US since it just came out. For convenience sake since aquacave carried test and supplements I ordered both. My first choice is Marinedepot since they are the closest to me, but they didn't have the test kit.

I am still anxiously awaiting srusso's write up to have a better understanding on why he thinks this may be a fix to an imbalance problem. I am sure I will have a little more faith in it working once I read it.

I am not ready to post it, however I am happy to send you a draft copy. Looks like this thing it becoming more then I even knew... PM me your email and I will send it to you, would like to know what you think...

[srusso]

Ace25, forgot I already had your email from a while ago. Check it... :-)

[SantaMonica]

I forgot to add that I also started mixing vinegar with the kalk at about the same time I stopped testing. The vinegar might be contributing to the P flux.

1) this still does not explain Ace's bare-bottom, no rock frag tank with rising P

True.

2) I would like to understand the specific mechanism of how P is absorbed and leeched from rocks.

It binds with other things like calcium, etc. Higher pH causes P to precipitate out of the water, and bind, where it cannot be measured. Lower pH dissolves the bind, and makes the P bio-available again in the water, where you can measure it.

3) excessive feeding should also lead to rising N

Not if your theory of "more N reduction than P reduction in tanks" is true.

[srusso]

FYI- Dosed 60ml of potassium a few hours ago.

[Garf]

The Redfield ratio states a 16:1 nitrogen to phosphate ratio;

http://en.wikipedia.org/wiki/Redfield_ratio

But Randy H Farley says something more in the region of 100:1;

For example, Caulerpa racemosa collected off Hawaii contains about 0.08 % phosphorus by dry weight and 5.6% nitrogen. Harvesting 10 grams (dry weight) of this macroalgae from an aquarium would be the equivalent of removing 24 mg of phosphate from the water column. That amount is the equivalent of reducing the phosphate concentration from 0.2 ppm to 0.1 ppm in a 67-gallon aquarium. All of the other species tested gave similar results (plus or minus a factor of two). Interestingly, using the same paper's nitrogen data, this would also be equivalent to reducing the nitrate content by 2.5 grams, or 10 ppm in that same 67-gallon aquarium

Anyone got a reasonable explanation ??