Phosphate in food

[MitchM]

Seeing as how P04 levels in our tanks seems to keep creeping up, I tried a test yesterday to see how much is in the food that we are feeding the inhabitants in our tanks.

I took a single 7 1/2 x 8" , 2.8 gram piece of nori and placed it in 1 liter of RO/DI for 24 hours at room temperature and tested the water before and after.

Before P04 was 0.0 ppm.
After P04 was 1.0 ppm.

The only nutrient export systems that I am using are protein skimming and water changes, which are not enough as I am seeing more cyano growth and small patches of hair algae appearing.
I would like to get some macro algaes growing, but my sump and main tank have large algae eating fish in them, most of which are being transferred to a new system soon.
I'm looking forward to seeing if planting some macros will work to take up the P04 fast enough to compensate.
I measured my tank water and it showed 0.5 ppm P04 before the water changes that I am now doing.
I'm going to do the same test with some frozen mysis, rinsed and unrinsed next.

edit:
18 grams (about a tablespoon) of Piscine mysis, unrinsed, showed about 2.0 ppm in the same test. :eek:

edit:
18 grams of frozen mysis, thawed then rinsed briefly in R/O brought the weight down to 14 grams. P04 was a little over 1.0 ppm.

Mitch

[Delphinus]

Very ... illuminating. 1.0ppm from one sheet of nori is impressive.

[Canadian Man]

Stop feeding nori! :biggrin: As much.

Yes I'm serious.
I have stopped feeding my whole sheet of nori every day and have cut back to 1/2 sheet every 4 to 5 days.

This has been a big change for my huge algae eating population, but, they are all still very fat and have been for the 2 months I have been doing this.

Just a thought.

[MitchM]

What are they eating instead, Jonathan?

Mitch

[AJ_77]

Good question - another question I have is, would it be safe to multiply liters and get the likely effects a sheet of nori (unconsumed) would have on 100 gallons of water?

Also, could you do the same test in some tank water, Mitch? I know, I know... :biggrin:

[MitchM]

Good question - another question I have is, would it be safe to multiply liters and get the likely effects a sheet of nori (unconsumed) would have on 100 gallons of water?

Also, could you do the same test in some tank water, Mitch? I know, I know... :biggrin:

I'm sure someone could come up with some sort of math equation for P04 in ..P04 out. :mrgreen:
Do you want new tank water or old, Alan?
I've only commandeered one measuring container from the kitchen for now, I'd be pushing it for another.. :mrgreen: , and right now it's got mysis in it... :smile:

Mitch

[AJ_77]

It would be simple multiplication, if the relationship is the same per volume of water. It may behave differently when immersed in a bath-tub full of RO, for instance (or not)...

And I guess new tank water, thanks. :biggrin:

If you need containers, I've been squirrelling away a couple... if my wife sees me use anything for the tank, she now sets it aside as "not fit for human use" - and it becomes fishroom property. :mrgreen:

[EmilyB]

I don't think it's a good idea to leave unconsumed nori in a tank for more than a couple hours, and never have.

I wouldn't ever cut back on what my fish consume however.

Do a water change.... :rolleyes:

[AJ_77]

I don't think it's a good idea to leave unconsumed nori in a tank for more than a couple hours, and never have.

So how much do you put in at a time, and how long then does it take for your horde to finish it off?

[EmilyB]

LOL Alan, it takes them about a half hour to consume a 2 x 4.

1-2 flake feedings, one frozen feeding, and sometimes a pellet feeding.

[Delphinus]

How much do you think consumption of the food would impact the PO4 cycle?

[EmilyB]

I'll put a poop collector on Moo and let ya know.... :lol: :mrgreen:

[Canadian Man]

Mitch, They are constantly foraging on the rocks/walls of the tank and Chevy eat's the sand and of course other fish poops :rolleyes:

I do feed flake every day as well as mysis.

Deb. I'm glad to hear you would never cut back on the feeding of your fish. I did, and, well they are not suffering nor is the tank as a whole.

Oh and I do do waterchanges :rolleyes:

[MitchM]

Randy did an article a couple of years ago on phosphate, and here are a few paragraphs:
Phosphate Sources in Reef Tanks

Organic phosphorus compounds, as well as orthophosphate, are so prevalent that any natural food will contain significant concentrations of phosphorus. Flake fish food is typically about 1% phosphorus (3% phosphate equivalent) by weight. Consequently, if 5 grams of flake food is added to a 100 gallon tank, there is the potential for the inorganic orthophosphate level to be raised by 0.4 ppm in that SINGLE FEEDING. That fact can be a significant issue for reef keepers: what to do with all of that phosphorus?

If the food is completely converted into tissue mass then there will be no excess phosphate. But much of the food that any organism consumes goes to provide energy, leaving a residue of CO2, phosphate, and a variety of nitrogen-containing compounds. A fish, whether it is an adult or a growing juvenile will consequently excrete much of the phosphorus that it takes in with food as phosphate in its waste. Of course, overfeeding will result in more delivery of phosphate than will lower feeding levels.

For those interested in knowing how much phosphorus is being exported by macroalgae, this free pdf article in the journal Marine Biology has some important information. It gives the phosphorus and nitrogen content for 9 different species of macroalgae, including many that reefkeepers maintain. For example, Caulerpa racemosa collected off Hawaii contains about 0.08 % by dry weight phosphorus and 5.6% nitrogen. If one were to harvest 10 grams (dry weight) of this macroalgae from a tank, it would be the equivalent of removing 24 mg of phosphate. That amount is the equivalent of reducing the phosphate concentration from 0.2 ppm to 0.1 ppm in a 67 gallon tank. All of the other species tested gave similar results (plus or minus a factor of 2). Interestingly, using nitrogen data in the same paper, it would also be equivalent to reducing the nitrate content by 2.5 grams, or 10 ppm in that same tank.

The entire article is here:
http://advancedaquarist.com/issues/sept2002/chem.htm

So how are you exporting YOUR phosphates?
:smile:

Mitch

[danny zubot]

Mitch said: So how are you exporting YOUR phosphates?


That is a very good question. Myself and many other reefers don't have a whole lot of macro algae for nutrient export. It would be really helpful to devise a general idea of how much macro would be needed to export a given amount of PO4. To answer Alan's question.....get the likely effects a sheet of nori (unconsumed) would have on 100 gallons of water?
With the same sized piece or nori you'd get a 0.0026ppm increase in 100 gallons or 380 litres of RO water.
An interesting experiment would be how much PO4 a 2.8 gram (equivelent size to the nori) piece of macro algea can export in the same 24 hour period. Then multiple that by the size of tank.

[Delphinus]

Agreed Mitch, it has to go somewhere.

Despite its pitfalls macro algae harvest I think has some benefit. I think one key element is discipline: since sporulation presumably releases back a lot of what was previously absorbed, and since you cannot guarantee the prevention of sporulation, a better focus is mitigation of the damage this would cause (long winded way of saying, if you prune often, there's less of it at any moment to dump goo into the water column).

The other pitfall that is maybe not as easy to address is the issue of allelopathy. I've found, particularly with fast growing corals such as Acropora and other SPS, that the mere presence of some macroalgaes such as caulerpa, is enough to to negatively impact the growth of SPS.

In my case I've found proximity to be a key factor, so a remote macro harvest area should likely address the issue somewhat. I'm sure it's not a perfect solution and I'm guessing that although running carbon and perhaps other absorption resins may also aid in this aspect, I'm confident none of it is a true "silver bullet" solution.

It could just be however, that the positives outweigh the negatives (if properly managed). Although ... it's probably not the worst thing in the world if (at least some of) your SPS doesn't grow as fast as it could.

And of course there are other macros that may be less pervasive than caulerpa. Chaetomorpha seems promising to me, I've never heard of any real negatives with that one. The only thing I've found with Chaeto is that it seems to require quite bright light to grow effectively. Under moderate lighting conditions it is a slow grower (at least it has been in my systems, whereas in the past where I had it under HID it was a prolific grower).

Anyhow, those are my thoughts for the moment.

[MitchM]

I've added unrinsed mysis to the first post.

Mitch

[Rikko]

A new experiment might yield some interesting results:
what about soaking the sheet on nori in RO water for some period of time before adding to the display? The test already done could be your control, now maybe soak a sheet for 5 mins and another for 15 mins and then transfer them into a fresh batch of RO water and see what PO4 says. I know nori sheets are always a little flaky/dusty, so it could be that those ragged areas are dissolving quickly. The thicker sections of the nori might not release as much into the water (though admittedly it'll still end up in the poop).

I don't know if anyone's mentioned it in this post, but has anybody tried vodka for PO4 reduction? I haven't had enough of a problem to experiment with it yet, but the feedback I've seen on the RC Chem forum has been encouraging.

[Delphinus]

I've added unrinsed mysis to the first post.



Mitch, would you mind to repeat the test with rinsed mysis (and please describe the method used for rinsing, how long, etc. to try to put some kind of quantifier on it)? It would be interesting to see the difference. Thanks

[danny zubot]

Rikko said: I don't know if anyone's mentioned it in this post, but has anybody tried vodka for PO4 reduction?

I read that those tests were not done very scientifically and that the results were based on "eye balling" :eek: the various changes. I got the impression that the reefers doing the experiment were also experimenting on themselves. :redface:

What article did you read? I'd like to compare with the one I read.

[MitchM]

I've added unrinsed mysis to the first post.



Mitch, would you mind to repeat the test with rinsed mysis (and please describe the method used for rinsing, how long, etc. to try to put some kind of quantifier on it)? It would be interesting to see the difference. Thanks

Tony, I've got another 18 grams of mysis thawing right now, and once thawed, I'll be rinsing them in R/O just enough to get rid of the "juice". After that I'll re-weigh them and soak them.

I'm a little surprised at the results of the unrinsed mysis. I would have thought that the phosphate would have been tied up in the meat of the shrimp and would not have "leached" out into the water.

Rikko, I'm trying this out as far as what methods a typical reefkeeper would choose to feed the tank with. I haven't heard of anybody rinsing nori yet, although there may be a benefit there. I don't know if I'll try that test or not.

Mitch

[MitchM]

Tony,

As for your post regarding proximity of macros and SPS, I found that interesting, and it's something that I had forgotten about. Thanks.
I agree, macro algae harvesting (as in throwing it out and not feeding it back to your fish) is only one part of the equation.
Randy mentioned that skimming is another one, and for some of us, the only real means of nutrient export.
One problem with using a protein skimmer is that the suspended detritus/DOC's actually have to make it to the skimmer in order for the skimmer to do it's job. In a high energy, SPS reef/bare bottom set-up with tons of water flow and turnover it's not so much of a problem, but if you add a DSB, densely packed rock piles and some LPS, all of a sudden you have areas of low flow where detritus can build up and cause nuisance algae problems over time.
You could have the best skimmer in the world, but if you have low-flow-only LPS, the detritus will build up and never get to the skimmer. That's where macro algaes could help out, I think.

Just for fun, I tested the P04 in my skimmate. 10ml of skimmate in 1 liter of water showed a reading of .25ppm. That's what, 25ppm P04 skimmate... :mrgreen:
Glad to get that out of my tank!

Mitch

[Rikko]

Rikko said: I don't know if anyone's mentioned it in this post, but has anybody tried vodka for PO4 reduction?

I read that those tests were not done very scientifically and that the results were based on "eye balling" :eek: the various changes. I got the impression that the reefers doing the experiment were also experimenting on themselves. :redface:

What article did you read? I'd like to compare with the one I read.

This was the thread I'd been reading, though there were others I didn't bookmark:
http://reefcentral.com/forums/showthread.php?s=&threadid=288714

It's since grown rather... Large. From what Randy has said it sounds like you need to find the acceptable alcohol input for your particular tank and find it gradually. Add it with a dropped and test your phosphates over time.

I'll give it a shot when my phosphates become a concern.

[MitchM]

Thawed and rinsed mysis results added.
The P04 measurement was less than the frozen number, but I think that it was due to the reduced amount of material, not that it was due to the "juice" being any worse.
I'm not sure whether it's beneficial or not to rinse the frozen mysis first, as some people do. The particle size of the juice could wind up being bacteria food, or the corals could indeed be benefitting.
Any opinions?

Mitch

[StirCrazy]

The particle size of the juice could wind up being bacteria food, or the corals could indeed be benefitting.
Any opinions?

Mitch

I agree with you on this but I only feed mysis once a week. If I was feeding every day I might be tempted to rinse.

Steve

[Delphinus]

Just curious Steve, how much mysis do you put in when you just feed weekly?

[StirCrazy]

Just curious Steve, how much mysis do you put in when you just feed weekly?

I cut a chunk off that is about 1cmx1cmx1.5cm I would say. I use it as more of a treet for them and use pellets the rest of the time.

Steve

[rickcasa]

great info

[Dyspnea]

8 year old thread from the dead...

[rickcasa]

There's gold in them thar dusty old posts.
As a newbie reefer, I'm just soaking in all these great info.
I'm sure theyre still valid.

[SeaHorse_Fanatic]

After my friend Chin tested the PE mysis and found high phosphate levels, I've always washed/rinsed off all the frozen foods before squirting into the tank after adding Selcon and Garlic Xtreme.