Scrubbers DO NOT export Phosphorus

[Amphiprion]

http://www.nature.com/nature/journal...ture07659.html

A good article. Suggests that there are species of algae that are able to exist in even the leanest P situations. This somewhat fits into the algal succession on scrubbers that I've noted. It also brings into question the whole "if you have algae, nutrients are too high." While I've known for a while how phosphorus works, I still think this statement isn't quite accurate. It certainly doesn't explain the miraculous growth of algae in very pristine locations where there is no cropping or competition.

http://link.springer.com/article/10....0922-1?LI=true

This article suggests that typical criteria for trophic states may not be inclusive enough and that everything may be much more complicated. Makes one wonder what this would mean for the usual ideal trophic designation of a reef would be... as in are they as truly oligotrophic as we idealize them, at least in the traditional sense... Interesting nonetheless and food for thought.

[MorganAtlanta]

Okay... I've waded through most of this thread, and I'm a bit confused as to what the point being discussed is. Is it that harvesting algae from the system does or does not remove *any* phosphorus, or that it does not remove *all* phosphorous, or that it only removes *some* of the phosphorus, and the question is how much?

Arguing that it doesn't remove *any* seems silly, since the algae harvested is made up of organic matter that surely contains phosphorus.

Arguing that it doesn't remove *all* phosphorus, may be a bit silly also, since most tanks have other sinks for phosphorus (Ace25's maybe excepted), this is obvious.

Arguing that it removes only *some*, but the question is how much, seems reasonable, and easy to answer without knowing much about the various fluxes of phosphorous inside the system. That's just a simple mass balance. Measure what you put in the tank as food and measure what you remove from harvesting (and/or skimming, water changes, etc.), and there you go.

What actually happens inside the tank is irrelevant in a first order black box model. Of course, things are more complicated than the black box model, but until someone has done at least that, theorizing and speculating and quoting somewhat related studies from other fields seems less than useful.

[xerophyte_nyc]

Arguing that it removes only *some*, but the question is how much, seems reasonable, and easy to answer without knowing much about the various fluxes of phosphorous inside the system. That's just a simple mass balance. Measure what you put in the tank as food and measure what you remove from harvesting (and/or skimming, water changes, etc.), and there you go.

Yes and no. Simple mass balance would provide us with a net change in P during a set time interval. But it does not take into consideration the P that is being shed by the algae during that time period. The continuous shedding of P just fuels the bacterial-algal cycle.

I don't have the means to figure out exactly how much P is in my food, and then how much P is in the algae that is harvested. I might be able to come up with a rough estimate simply by getting a dry weight of a weekly algae removal, then extrapolate how much P is there by weight, and then further extrapolate how much of a food equivalent it is to see whether P in the algae is the same, higher, or lower. It would be neat if someone could do this accurately.

But there is still the issue of "chasing" phosphates. By the time algae uptakes P, it has already been processed by bacteria, and the algae is also continuously shedding P. It's just not efficient at all, in those cases where the goal is to significantly reduce P. In a heavily fed tank, where one seeks to gain nutrient control, an ATS helps to keep levels from going through the roof. But an ATS doesn't really work towards P reduction over time.

The simple fact that in general we are continuously harvesting algae means there is plenty of P in the system feeding that growth. I am not by any means suggesting an ATS is a bad thing. I'm just pointing out that it is incorrect to say that an ATS will lower net P in a tank over time. It will keep it stable, which for a high bio-load tank is beneficial.

[Garf]

What about Photosynthetically induced phosphate precipitation? This is thought to be a major player in reducing phos levels in the ocean, which may be utilised in the ATS.

[xerophyte_nyc]

What about Photosynthetically induced phosphate precipitation? This is thought to be a major player in reducing phos levels in the ocean, which may be utilised in the ATS.

Thinking out loud here...if pH is high enough to precipitate P out of solution, it would then probably bind to open sites within the substrate (rock or sand). As long as pH remains high enough (I believe around 8.6) then the P is locked up, which would be great - the sand could become a phosphate sink and then it could be replaced. But if the goal is to keep the P safely bound, how do you keep pH elevated consistently, without also considering that calcium will start to precipitate onto equipment? If you are suggesting that locally the scrubber screen physically traps this P, it would make sense - not unlike what I already mentioned about the screen perhaps being a very good detritus trap.

Maybe the ATS is nothing more than a glorified filter sock, trapping detritus and other particles so well that it supports fantastic algal growth.

[Bilk]

Thinking out loud here...if pH is high enough to precipitate P out of solution, it would then probably bind to open sites within the substrate (rock or sand). As long as pH remains high enough (I believe around 8.6) then the P is locked up, which would be great - the sand could become a phosphate sink and then it could be replaced. But if the goal is to keep the P safely bound, how do you keep pH elevated consistently, without also considering that calcium will start to precipitate onto equipment? If you are suggesting that locally the scrubber screen physically traps this P, it would make sense - not unlike what I already mentioned about the screen perhaps being a very good detritus trap.

Maybe the ATS is nothing more than a glorified filter sock, trapping detritus and other particles so well that it supports fantastic algal growth.

This all sounds correct I believe. I think messing with the pH may also disturb the calcification process - it being too high or too low to allow proper calcification.

I've been trying to do some research on why Zeovit systems require a potassium to be as close to 400 as possible. That system relies on a gererally alk level than what many people sun - somewhere around 7dkh. I received a response from one person with this link, which I cannot access. Maybe one of you can access it. It's well above what I would understand any way Link Somehow this may all tie together. Or maybe not LOL

[Ace25]

I found one way to drop phosphates down to 0 quickly... by mistake. I would never recommend anyone doing what I did because it was a major screw up on my part, but the results were shocking to me.

What I did is I put 2 cups worth of GFO in a BRS dual reactor. Since these reactors suck balls, after the first day the first canister was full of air causing the reactor to not work properly. In the process of clearing the air out of the canisters (turning the valve off/on full blast quickly), I must have left the valve open a little to much which ground up the GFO into dust which then got into my system (couldn't see it, but since there is only 1/4 left in the canisters from what I started with I know it made it into the water). The very next day I came home from work to a huge bacteria bloom in my tank, almost milk white. I panicked, turned off the reactor and did a 20G water change quickly. Next day, water is absolutely crystal clear and my phosphates on that system when from .29 to 0.00 on my Hanna meter (tested 3 times to verify).

I have no idea what exactly happened, I can only guess. My guess is the GFO dust got all over the rocks and substrate and somehow bound up the phosphates that has accumulated (the algae in the display literally melted away overnight and I could see a red tint on the algae from the GFO dust).

The worst part though, I lost 1 fish this morning. It was my oldest fish, a 13 year old yellow wrasse. Not sure if my mistake caused the death because it was already 5+ years past its life expectancy. When I pulled the body out this morning it looked healthy and full (nothing wrong with its skin/eyes/fins and had a fat belly) but the fish has been acting very odd for the past year. The fish turned into a total tweaker fish where anytime I would even walk close to the tank it would freak out and go nuts in the display trying to jump out and scare all the other fish. Either it was just old age or a combination of old age and the GFO dust, but either way while it sucks to lose my oldest fish, I am not too heartbroken because the fish has been causing problems for me and my other fish for over a year now.

[Floyd R Turbo]

How did your reactor will with air? I don't have one of these but isn't it just like a DI canister? Even if you get air trapped in the canister, the water would still get pushed up through the GFO and any air would escape through the outlet. Unless you plumbed the inlet into the outlet, which would trap air in the sleeve insert.

[Ace25]

Hard to describe, but it is the way I have the reactor plumbed into my return line. Any air bubbles that hit the return pump always end up in the reactor and when the first canister outter sleeve is all air it makes the media in the canister behave strange, in turn making the second reactor not move at all. I will never recommend a dual reactor to anyone now that I know the issues with them. Single reactors are the only way to go to ensure they function properly and consistently.

Reactors work just like DI canisters, water comes in and down the outter sleeve and comes up through the bottom of the inner container and out the top. If the flow was reversed it would just push all the media out the bottom of the container, into the outter sleeve, and up into the next reactor.

[Floyd R Turbo]

That's odd. I've never heard of anyone complaining of their dual reactor not working right.