Phosphate impact on corals?

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happysalt

happysalt

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Hi so I have had my reef tank up and running for 9 months or so. The results from testing today are:

Nitrates - 2.5
Phosphates .37
alk - 9.6
Calc - 420
Mag - 1375

I have been battling to get the phosphates down recently and just started running GFO in a reactor. Phosphates were up as high as .49 as of a week ago. Every one of my corals (LPS, SPS, Zoas, Mushrooms) as well as my anemones seem perfectly happy. Should I just strive to keep my phosphates in place or should I really lower them. Just wondering what negative side effects to my corals should I be looking for?
 
Deltec
Ok, And i understand the Algae issue associated with this level of phosphates, I also ordered some of the brightwell aquatics Phosphate-e as well if I need an extra kick to bring the phosphates down. I would like to get it to the ideal range sooner rather than later.
 
Tidal Gardens
It’s hard to say. I run a very large system, with over 100 fish and a number of big SPS colonies. The tank gets a lot of food. Although probably nobody else would notice, the tank just had not been looking quite right to me - not at all scientific, I understand. I had been having a bit of STN on two colonies and a pink birdsnest went RTN on me. I decided to send off a water sample for Triton testing. Sample came back almost perfect with one exception, high P/PO4. I am not claiming that was the sole reason. The pink coral, for example, had become too large and was self shading; plus other cuttings in the same system are fine. But certainly high phosphate is not ideal (mine was 0.195) so I’m running GFO to get it down. Have not retested, but already the tank looks better. Correlation, causation, dumb luck ..... who knows.

Interestingly, my chaeto has not been growing all that well lately, yet clearly there’s plenty of phosphate. Have to test for nitrate, that may be limiting growth.
 
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Nutramar Foods
Here’s an excellent article on this subject that you may find interesting

http://reefkeeping.com/issues/2006-09/rhf/index.php

Personally I’ve found this best single thing I ever did in my tank was to lock phosphate down with rhowaphos in a reactor to around 0.03ppm

Just remember you need to change the GFO regularly until the phosphate level drops after which it will last longer
 
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I don’t know that there is really any hard, fast number for either PO4 or NO3 that is truly optimal. Different corals have different tolerances and different demands.

The overriding theme of the mixed reef is ‘You can’t make everybody happy all the time’

Too much PO4 can limit calcification. Too little PO4 is deleterious to zooxanthellae. We can reasonably assume too little would be <0.1, and too much would be...? >0.4? It’s hard to say for sure, because different corals are found in different environments with different nutrient levels.

If it were me, with a mixed reef, I would be ok with 0.15-0.25.

There’s a tank that I do that, due to the client overfeeding beyond what even my awesome, oversized LSS can deal with, consistently has a PO4 of 0.5-0.75 (sometimes more). You would never know by looking at it. There are a couple of SPS that look good but aren’t great growers, and then there’s a chili pepper monti that you can just about watch grow. Everything else grows like crazy. Go figure.
 
I would say phosphates impact on a tank is determined by the age of the tank and amount of corals, strength of the light, and also the amount and type of food that's being fed. Typically in low light and newer tanks corals don't fair well with higher phosphates and an aged tank with a lot of corals can handle higher phosphates if it's fed well and lit well.
 
View ReefStash's latest YouTube video!
I've been testing my phosphates and nitrates for the past year since my GHA was out of control. Salifert test kits, phos was up to 2ppm and nitrates topping around 40ppm. They are currently, phos under 1ppm and nitrates 20ppm. Chaeto in the sump has been doing well at bringing them down.

The hammer in my profile pic grew from one tiny head to about a dozen heads in these conditions in a year and a half, I even have a couple baby heads from this colony growing out. Red and green striped mushrooms are weeds, can't kill them in my tank. Green nepthia as well as colt coral grows fine. Brown/green palys do great as well. I've added some zoas recently and some are multiplying.

Brain frags...meh. I've killed/ stressed a couple, due to several issues, maybe phos related, but maybe kalk O.D.

I tried a purple monti frag, mostly killed that, but there are a few polyps still hanging on.

The tank has been setup since 2010, with some rock between 13 and 18 years old.
 
I think the consensus now is new tanks should shoot for low phosphate like below 0.1 ppm. Older tanks over two years can go with higher phosphate without issue. It’s really unclear what nitrate and phosphate do to corals in my opinion. We have see great tanks under all kinds of conditions.
 
Scrubber_steve said:
I know there are people who are keen to point some great tanks that have quite high PO4. But these tanks are great despite the high PO4, not because of it.
Click to expand...

Probably true! I remain unconvinced (from personal observation, so grain of salt) that elevated phosphate levels directly affect corals, rather indirectly as a consequence of algae overgrowth. No question that lower is better than higher though.
 
Tidal Gardens
Scrubber_steve said:
I thought that may have been the case. ;):)

I know there are people who are keen to point some great tanks that have quite high PO4. But these tanks are great despite the high PO4, not because of it.
Click to expand...

I have to agree. It’s scientifically proven that from a PO4 level of .12 and above, calcification is inhibited. Google RHF’s phosphate article. Personal experience, anecdotally, proves to me that SPS do not like it higher than .1 and are as equally unhappy (and can burn) under .02. Just MHO thru observation.
 
In my opinion <0.01 ppm is phosphate starvation and >0.1 is excess Phosphate, so there is quite much room to live in. Excess phosphate is not as bad as it is frequently meant to be but in SPS it makes the branches thin and the skeleton brittle.
 
One more comment from my side: If you have Acropora look at them. Acropora spp. are the corals most sensitive to sinking phosphate concentrations. Once adapted to high phosphate concentrations they may stop growing and even show STN with sinking phosphate concentrations.
 
Tidal Gardens
Hans Werner what do you think about the tanks that have extremly high phosphate levels and still grow acropora with thick strong branches? Like thales tank? Do you think the more brittle branches you are talking about is because of faster growth or because of something else? There is an article about muricata sp. growing faster in higher phosphates than lower, which doesn't prove much for the overall species but is interesting.
 
Thales tank is here if you haven't seen it guys. Rich Ross (thales) did a nice speech at our meeting a while back on this tank and the nutrient levels. But most of it was just him questioning normal beliefs on phosphate, he never really explained what he thought was happening in his tank to be able to keep levels that high. So I figured I would toss up the question here.
http://packedhead.net/2012/evolution-of-a-10-year-old-reef/
 
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