Myth Busting! False positive reading on phosphate in your aquarium with presence of algae?

by Richard Back 

This day and age, there are plethora of information that are easily accessible by just using our fingertips and with advancement of search engines like google and social media like facebook, we get instant answers to our mysteries that usually leaves us puzzled otherwise.

We should ask this important question to ourselves. 
Is everything we find online all true? How do we know who to trust? But it sounds so good, logical and true! 

Luckily, I have some amazing friends who are very knowledgeable, respected authors, scientists, professors and gurus in the industry that usually assists me in my quest for truth and knowledge for our aquariums. I will share my conversation with them (via video,s chats or facebook conversations) with you guys here in our new Myth Busting blog series and to correct few misinformations and misunderstandings.    

This discussion/question was asked because I experienced little TN on my SPS after verifying all the numbers, I wanted to make sure the usual 0.4+/- variations from my Hanna test kit, if there was any other variables that I should consider. 

Does having algae present in our aquarium give our test kits false positive reading?  It seems to be common belief these days that having green hair algae or any in your display tank messes with our readings.  
(Whether in our display or placed in refugium or in designated container like algae scrubber. )  

Julian Sprung : People say... that sounds like a good proof of concept. Julian say that what people say is BS. 
Presence of algae does not give a false reading on phosphate kits. That is people trying to rationalize their mental construct of phosphate causing algae growth and testing showing no phosphate present. The truth is that you don't need much phosphate in the water to stimulate algae growth, and of course algae may utilize phosphate bound to calcium carbonate substrates (rock and sand), employing enzymes or even symbiotic bacteria to liberate it.

Boomer William Wing : Ditto Julian. I am always amazed in this hobby at some of the false statements made on many things, which are just urban legend and people just don't understand. And even after years of explaining NO, some people still BELIEVE in them 

Julian Sprung : Phosphate is only one part of the "cause" of algae growth. Refugia and scrubbers effectively relocate the algae-growing area, provided that they are illuminated sufficiently. If the light is brighter per surface area in the Display tank, the algae will grow there preferentially.
(Hence no algae present in your display tank for those people who believe and fear utilizing algae in refuge, reactors and in scrubber will have a risk of having them overtake your tank.)

​Sanjay Joshi: High nitrates or Phosphate do not cause algae growth by themselves. Phosphates in my tank run anywhere from .1 to .3 and I don't see algae. Tanks with excessive algae growth will often show low levels of phosphate and nitrates. I think is because it's bound up in the algae as they used it to grow lush and thick. Running a reef tank by chasing numbers will often get you nowhere good.

Boomer William Wing: And to add just because you have "zero" Phosphate and Nitrate does not mean you can't or won't have a algae issue. The nitrates and phosphate can be sucked up as fast as they enter the water by any means.
Of course your kit only tests for Orthophosphate and no the other forms , ie, Meta, Para, Organic, etc. You need a kit like I use to have and gave to Randy Holmes Farley that test them all. Furthermore, many algae can extract other, at least phosphate, by other means,. Some can do it extracellular and convert them to Ortho.

Craig Bingman : So there is a potential detection issue here. I think that most of the phosphate scavengers prefer to pull out inorganic phosphate. Most of the phosphate in the water of a typical aquarium (and I did this work before the phosphate scavengers were out there) was in the form of organic phosphate. Both inorganic and organic phosphate are available to organisms. I'm not quite sure how quickly those pools interconvert, but the total phosphate pool was pretty consistently 3-5x larger than the inorganic pool. There certainly is interconversion, and certainly drawing down the amount of inorganic phosphate in the system will decrease the size of the total phosphate pool. As people have noted, it really doesn't take much phosphate to make a lot of algae, and there are places to get besides the soluble pool. There is a lot of surface-bound and detrital phosphate in a typical reef tank, and obviously that isn't detectable by simple water testing.

My mind after hearing Craig : Blown. 

Conclusion 

Having algae in your system whether in chaeto reactor, algae scrubber utilizing turf algae or having diverse macro algae in your refugium will NOT cause false positive readings in your phosphate tests.  Also 

We also found out that having different types of algae, even the unwanted ones like turf algae in refugiums, reactors or in scrubber will not transfer them into our display tank as long as we provide lighting that they thrive in their designated area.  

Long as you are in the acceptable numbers don't chase them too much.  It will lead to demise of your tank. (Sanjay)

So this myth and urban legend of false positive reading in presence of algae is BUSTED. 
Very detailed video is coming soon so stay tuned for that one! 
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If you guys have any myth or urban legends in reef keeping that needs to be verified or busted, please let me know.