Phosphate problem

[rjjr1963]

I'm using the Hannah ULR phosphorus checker to monitor my phosphates. They were running just a bit higher than I wanted at .104. I bought a small Cad Light reactor and ran a little bit of GFO. Within a week it dropped to .009! I discontinued the GFO and now I'm wondering if I need to raise the phosphate or just let the tank adjust itself. I've had a slight algae problem so I've been feeding less and shortening the light duration. Nitrates are zero, calcium is 532, magnesium is 1360, Alk is 9.4 dkh and PH is 8.2.

 

[Dan_P]

The level of phosphate you are dealing with is near the limit of detection and quantitation for the Checker. The exact level is a bit uncertain, so, no point in trying to fine tune it. Also, algae can still grow even at this level of phosphate, just not at its maximum rate. Most aquarist seem to have good results just keeping phophate levels below 0.03 ppm, though some feel better keeping it at or below 0.01 ppm.

 

[tmz]

I prefer 0.02 to 0.04ppm PO4. Overly agressive PO4 removal can starve nusiance organisms but will also starve desireable organisms.

 

[scooter31707]

How old is the tank? Did you start with dry rock? Possibility the rocks could still be leaching phosphates.

 

[rjjr1963]

How old is the tank? Did you start with dry rock? Possibility the rocks could still be leaching phosphates.

It's almost a year old. I started with wet live rock from the LFS. My problem is that phosphates are too low.

 

[tmz]

I'd let it adjust itself. Food will bring in quite a bit of phosphate and biologically available nitrogen. How are the corals doing?

 

[rjjr1963]

Mostly the corals are doing great. I have one montipora that is losing its fluorescent green. I've run out of regent for my Hanna checker so it will be a couple days before I can check it again.

 

[tkeracer619]

Gfo is powerful stuff. Just do your thing, I suspect by the time the reagent come in your numbers will be a bit higher.

 

[tmz]

It sounds like it will be ok with feeding and some time witout GFO . Some have dosed phosphate after too much GFO or lanthanum chloride but that's usually when corals are paling a lot ,even then removing the gfo usually takes care of the problem. Seachem flourish phosphorous is a product some have used.

 

[jonwright]

The idea of dosing phosphate blows my brain to bits.

 

[Timfish]

The idea of dosing phosphate blows my brain to bits.

Try reading these papers:

https://www.researchgate.net/public...by_giant_sea_anemones_Demand_outstrips_supply

http://jeb.biologists.org/content/214/16/2749

If you look at the distribution of surface PO4 from as high as .7 mg/l away from reefs to an average of .13mg/l on reefs it seems pretty obvious reef ecosystems are using large amounts of it.

 

[tmz]

Living things need phosphate along with other nutrients and elements . The trick is getting enough in a constant supply without overloading a closed system to a point where nuisance algae and other detrimental effects from excess are manifest. The major source in tanks is food.

This is why PO4 control is on the agenda for most aquariums. True zero PO4 is not desireable,IMO, however, though often pursued to eliminate algae since it is known that single celled algae is limited below 0.03ppm. So called ultra low nutrient systems rely on this zero based strategy with success but do require a plethora of supplements. Algae varies by species in it's minimal needs for phosphate and excesses will spur growth but many algae are oligotrophic and can do well at very low PO4 levels.
IME, a level of PO4 between 0.01 and 0.04 ppm minimizes nuisiance algae to minimal amounts while supporting a wide variety of corals. Some do like it higher .say .1 or so but that usually resluts in more nuisance algae in my aquariums.

 

[Griff500]

Zero nitrates would concern me more given your phosphate level. Wouldn't feeding more take care of matters for you?

 

[tmz]

Zero nitrate may indicate a nitrogen deficiency;nsw is around 0.2ppm ; but nitrate isn't the only source of nitrogen;ammonia and nitrite for example

Food will add both nitrogen sources, phosphate and other nutrients and trace elements.

 

[rjjr1963]

I did start feeding more and the phosphates have come up. I got my Regent last night it's at .09 now a little higher than I'd like but I will go back to normal feeding and just monitor things for a while.