Low Phosphorus

[cperry7467]

This is a new one for me, not sure if I actually have a problem I need to address or if this is fine. Details of the tank:

90g Display + 40g Sump
Primarily SPS with PB Tang, Flame hawkfish, pair of clowns, coral beauty, melanarus wrasse, also BTA's
No filter socks
Light skimming
Auto feed spectrum pellets daily(x2) plus frozen cubes each evening
Chaeto in fuge
ATI Essentials
Rarely do water changes

The tank has been well balanced for a while, I don't have to dose nitrates or phosphates, no algae problems, great SPS growth and colors. No GFO, just ROX carbon. I haven't killed a coral in over a year. It's about as low maintenance of a tank that I've ever had.

I use ATI ICP tests and just got the results of my latest test which shows my Phosphorus at 9.42ug/l and phosphate at .03mg/l. According to ATI the phosphorus level is low. I've never really paid attention to phosphorus before, just phosphate. Is there something I should be doing to raise my phosphorus?

View attachment Analyse49521.pdf

 

[csb123]

That phosphate is fine. If it were me, and things are as good as you say, I would NOT CHANGE ANYTHING.

 

[PatW]

The amount of phosphate in the water is not the big issue. Sea water has very low phosphate levels. But reefs do fine. Reefs usually have pretty high water flow and even though any volume of water going over the reef has low phosphate, enough water goes by that corals and algae can grab enough phosphate. What is important is nutrient flow and are the corals and their algae getting enough to drive the system.

In my system, I have vigorous nutrient export. I dose phosphates and nitrates. They go into the system and out again. My corals can grab enough for their health as the nutrients flow through.

So if you are adding phosphates in the form of food and the fish are eating it and pooping it out, your corals could be doing just great even though the concentration of nutrients in the water is low.

So how are your corals? Are their polyps nicely extended? Are they growing? Are they colorful? If the answer is “yes” to all three, I would say that you are doing fine. You probably have good nutrient flow.

 

[rkpetersen]

Agree, that phosphorus level is fine.
Also, phosphorus and phosphate are interchangeable. (Or at least, they are treated that way by ICPOES labs.)
ATI doesn't actually test phosphate; the number given is just a calculation based on the phosphorus reading.
Phosphate (ppm) = Phosphorus (ppb) x 0.00306

 

[Randy Holmes-Farley Verified Community Expert]

Just to pile on, it is fine and I would not consider higher levels better.