Bio-Pellets, GFO, and PO4

[JSB]

I have been running GFO on my aquarium since it was set up last fall, but I could never get PO4 below .03. I decided to move to bio-pellets several months back, and have been making small changes to the configuration (amount of pellets and flow) every month or so to dial it in. Regardless of what I have done, PO4 went to .08 and has never come down.

Today, I just happened across a thread in another forum indicating that the Red Sea Coral Pro PO4 kit that I am using may have a faulty Reagent A dropper, and instead I should use .5ml of Reagent A from a syringe instead of the 10 drops from the bottle. I did the test this way, and now I am reading 0ppm. So now I have to wonder how long I was at zero, and how much tech I have added to fix a problem that did not exist?

Even though PO4 is 0, NO3 is still around 3ppm and has not changed much since since I added the BP reactor. So I believe the PO4 is generally being removed by the GFO and smaller amounts by the BPs. I believe this is true as I have increased the bio-load in the tank, and subsequent feeding but NO3 is not climbing.

Noting that I have recent increase (somewhat dramatically) the flow on the BPs, I believe that they will become more and more effective at reducing NO3 and PO4. So here is my question. Should I just stop the GFO completely, or cut it back gradually over time until the BPs kick in? I don't want to overstrip the system of PO4 and inhibit growth, but I don't want to do anything to shock it either.

Opinions?

 

[Ken m]

Could you post the link to that article about the red sea test kit. I have almost the same problem. I am running gfo, bio pellets in a reactor, and just this week I added a algae scrubber. My phosphates will not drop under .08
Ken M

 

[JSB]

They probably won't let me post it here as it is on Reef Central. Just go to the red sea support form and search that forum for PO4 and .08. You will get to it very quickly. But for the "what you need to know" info, instead of using the dropper, dispense .5ml of the reagent a, and then the test should be accurate.

 

[Ken m]

Wow did that and got 0 for phosphates. Makes sense considering all the things I use for po4 controll

 

[JSB]

Yeah, I was wondering for a long time what on earth I could be doing wrong.

 

[H@rry]

I never did trust PO4 test kits and really considered them pretty worthless so I quit trying to test. I have been noticing some RTN problems with acros in one of my tanks that I couldn't explain. I got a Hanna PO4 Checker last week and it tested .05. That pretty well answered my question. I found a little bit of GFO and put it in a sock in the sump and ordered some more. I'll check it again later on today.

 

[JSB]

How is that H@nna checker, H@rry? I was considering getting one myself?

 

[H@rry]

I like it. I checked all the tanks this morning and the GFO came today.

190 - .05 - added 2.5 more cups GFO
3 tank system - .03 - added 4 cups GFO
Frag Tank - .00 - (didn't add any GFO :clap2

This is consistent with what I read a week ago. The only difference was the 3 tank system tested .02 last week. This leads me to believe it's pretty reliable. I could probably explain the .00 reading from the frag tank as because I'm constantly removing water and replacing it plus there is no sand bed.

What does confuse me is that all the "experts" claim you can't really test for PO4 in the water column as it is consumed by organisms as it becomes available.