What is your phosphate management routine?

[marie]

Tony, I am pretty sure I have relatively high phosphates...I have cyano and numerous pest algaes trying to poke their noses in where the fish can't reach them but my corals grow like mad,...it would take a lot to convince me your sps problems are because of phosphates

[nlreefguy]

I would also love to hear others' perspective on this. I had a similar problem with growth and survivability with SPS in my previous tanks, and now in my current tank my SPS are thriving and growing despite the fact that as far as I know, I'm not doing anything any differently than in my previous tanks. Still using GFO and carbon, same circulation pattern, exactly same lighting, same water source, etc. So I'm most interested too, Delphinus. Sorry about directing the thread away from the original intent, by the way.

[fishytime]

I run Rowaphos(gfo) in a reactor
Cheato in the fuge
never have tested for phosphate

Phosphate test kits are a waste of money IMO.

[Myka]

The "I have never had a PO4 reading" option is quite irrelevant because I doubt anyone who voted for that option used a D-D Merc kit or another high sensitivity kit. A "zero" on a Salifert or Elos kit is not actually zero, it is simply "undetectable" with those low sensitivity kits. Even if you got a "zero" on a D-D kit, it is highly unlikely that it really is zero, it is also "undetectable" with the D-D kit. PO4 can also be taken up by algae in such amounts that there is little left in the water column to test at any given time.

Originally Posted by marie

The more animals and plants you have living and growing in your system, the more phosphates get taken out of the water column.

Precisely. If there is more phosphate in the water column than the plants (both "good" and "bad") and animals can take up then it becomes a poison of sorts. We don't like nuisance algae and cyanobacteria so we try to lower phosphate to the level that our plants and animals can handle. We have many methods of lowering phosphate; GFO, carbon sourcing (VSV, Fauna Marin, Zeo, etc), and competitive elimination (chaeto).

Your test kit (any kit) will only read the amount of phosphate in the water column that exceeds the demands of all the organisms in the tank. If you have nuisance algae, cyanobacteria, and/or chaeto growing in your system this expresses the PO4 difference between the kit's reading and the demands of the "good" organisms in the system. If your test kit is "not detecting" phosphate, and you have nuisance algae you do have an excess of phosphate.

Nitrate also plays a role, but we are discussing phosphate here. The two are usually quite intertwined, and in most discussions aren't of significance to differentiate.

Personally, I gave up my GFO. GFO has never been in my new tank. So I voted:
"I run a ULNS" [Zeovit, just starting the nutrient lowering full system]
"I test PO4 frequently" [with Salifert it is "undetectable", and has been so since shortly after the tank finished cycling]

[Delphinus]

I used a D-D kit and a colorimeter and voted that option.

In your opinion what is the difference between "undetectable" and "not present at this level" ? To me "undetectable" simply means "present in levels below the threshold for the reading category". In the case of D-D/Merck, the lowest value is 0 to 0.008 (which is VERY low IMO - as in, less than 0.01 - no other test kit, including the colorimeters can read to that low of resolution). One thing about the D-D/Merck though is that it is not a linear scale.

[Myka]

Hey Tony, I added some more thoughts to my post before I saw your reply. I'm bad for editing, and re-editing, and editing some more adding more thoughts.

Imo, the difference between "undetectable" and "not present at this level" is that "undetectable" admits the test kits' accuracy may be (probably is) lacking where "not present at this level" suggests a positivity that we really can't confirm.