Can Phosphate levels be too low for Coral growth?

[Bryan]

Tried GFO a number of times over the years and the result has always been the same, corals stop growing, fade in color and a few sucumb to STN, especially digitata and caps.

Could I be driving phosphate to such a low level that it is causing distress to the corals.

Without GFO , phosphate tests out at 0 on the Salifert test, I know Salifert is not the greatest kit for measuring low levels of phosphate.

Nitrate is always ~0 according to my Lamotte Nitrate test kit. I actually dose weekly with potassium nitrate to add a small amount of nitrate to the water column.

Other parameters are fine
Alk 3.2
Ph ~8.2
Salinity 1.026
Calcium 410

Carbon 24/7 and ozone is used. Comments. Anybody else experience the same.

[kev apsley]

The modern study of the physiology of coral symbiosis began with a series of elegant experiments done by C. M. Yonge on the Great Barrier Reef Expedition of 1929. Yonge showed that symbiotic corals take up phosphates and ammonia from the surrounding seawater by day and release them at night. In order to study this phenomenon in greater detail two of us (Thomas F. Goreau and Nora I. Goreau) supplied carbon in the form of the radioactive isotope carbon 14 to reef corals. During the daylight hours the zooxanthellae assimilated the radioactively labeled carbon and photosynthetically fixed it into organic matter at a rate that was dependent on the intensity of the light. Some of this organic matter was then "leaked" from the algae to the coral host. Subsequent work by Trench and Leonard Muscatine of the University of California at Los Angeles and by David Smith of the University of Oxford showed that the leaked compounds include simple nutrients such as glycerol, glucose and amino acids. These compounds are utilized by the coral polyps in energy-yielding metabolic pathways or as building blocks in the manufacture of proteins, fats and carbohydrates.

It has long been known that the rates of metabolic reactions are strictly limited by the rates at which waste products are removed from the immediate environment. In higher animals the task is accomplished by specialized circulatory and excretory systems. These systems are absent in the anatomically simple coelenterates, which rely largely on the slow process of diffusion to remove soluble inorganic waste products such as carbon dioxide, phosphates, nitrates, sulfates and ammonia. The zooxanthellae, however, need for photosynthesis the very substances the coral polyp must get rid of, and they are believed to actively take them up from their host

[kev apsley]

interesting read

http://www.globalcoral.org/corals_and_coral_reefs.htm

[Flint&Eric]

yes it's very possible. po4 is needed for corals to live. shoot for .02-.04. if you're running that low nutrient you may want to look into a hanna colorimeter to get more accurate po4 measurements.

how has the potassium nitrate been working in your system? are you adding it as a nitrogen source as well as K?

eric

[Sk8r]

That is actually one of the clearest explanations I have read.

[kirstenk]

I don't know but I do know that my tank is PO4 Limited. 0.00 on a Hanna ColorMeter for over a year. Whatever PO4 I have is being consumed very fast. I have tried feeding more and this just causes Nitrates to climb.

I feel its a problem but I have no idea what to do about it.

[kev apsley]

Originally posted by kirstenk
I don't know but I do know that my tank is PO4 Limited. 0.00 on a Hanna ColorMeter for over a year. Whatever PO4 I have is being consumed very fast. I have tried feeding more and this just causes Nitrates to climb.

I feel its a problem but I have no idea what to do about it.

do you dose Amino Acids?

[Horace]

What are you doing to bottom out the po4? If your using media, just use less.... if your using carbon source, then change up your dosing some. Getting more Po4 is truely not a hard thing to do

Oh and unless your no3 are sky high, I wouldnt worry about those either. no3 are pretty harmless it seems. I have seen some truely amazing SPS tanks with no3 ~50ppm! I always thought they would brown the corals out, but so long as Po4 is low, that just isnt the case.

[kirstenk]

Getting more Po4 is truely not a hard thing to do.

One would think.


I use Prodibio and AA are in the ReefBooster. I just started trying to tweak the dosage so I'll see where that gets me. I've heard that oyster eggs are loaded with PO4 so maybe I'll try them.

....nitrates are 10ish, after all the heavy feedings and I would agree, they don't seem to influence color at that level.

[jamesdawson]

Fauna Marin just released a GFO that keeps your PO4 level at .04 so you don't go to low. Aquarium Obsessed sells it and its reasonably priced!

James

[Bryan]

Yes, I am adding the Potassium nitrate as a source of N. I add about 3-5 grams twice a week. This raises my N to about 5 ppm but it is quickly used up in a day or so. It has imroved the growth of my Chaeto, unfortunately also incresed the growth rates of Valonia as well.

My rational behind adding KNO3 was to increase macroalgae growth which should cause a export of phosphate as well. I think it has worked too well when combined with GFO as the corals appear to be suffering.

I took the GFO off when i posted this thread and in a week I can honestly say the corals are looking better, however there has been an increase of algae growing on the glass at probably twice the rate.

Originally posted by Flint&Eric
yes it's very possible. po4 is needed for corals to live. shoot for .02-.04. if you're running that low nutrient you may want to look into a hanna colorimeter to get more accurate po4 measurements.

how has the potassium nitrate been working in your system? are you adding it as a nitrogen source as well as K?

eric

[Wiskey]

Originally posted by kirstenk
Getting more Po4 is truely not a hard thing to do.

One would think.


I use Prodibio and AA are in the ReefBooster. I just started trying to tweak the dosage so I'll see where that gets me. I've heard that oyster eggs are loaded with PO4 so maybe I'll try them.

....nitrates are 10ish, after all the heavy feedings and I would agree, they don't seem to influence color at that level.

You might want to try feeding more Nori specifically,.. or Phyto,.. both of those products are loaded with Phosphate.

I notice a big difference in my tank from when I do and don't feed Nori, in both color and growth.

Whiskey

[Bryan]

I would be skeptical about that claim from Fauna Marine.

Originally posted by jamesdawson
Fauna Marin just released a GFO that keeps your PO4 level at .04 so you don't go to low. Aquarium Obsessed sells it and its reasonably priced!

James

[Lobster]

This will sound silly, but I had this exactl problem. Quite severely actually, to the point my monitpora would "dry up" and not recover. Acros would grow extremely slowly, but never color up. I tried everything (including a ridiculous goose chase with potassium dosing) and finally found something that worked... the filth reactor!

My state of the art filth reactor is a 3G tank I found in the petsmart bargain bin. I set it up with sand, put a bunch of macro and messy critters in it, and kept it good and filthy (ie, moderately high nutrients). I'm able to "dose filth" into my bare bottom tank by dripping water into the 3G tank and let it flow back to my main tank's sump.

The reason it has worked well for me is that the two systems are not connected, so what happens in the filth reactor stays in the filth reactor. Unless I don't want it to.

[Flint&Eric]

lobster, that's actually a pretty neat idea...a constant drip of nutrients that's controlable.