Carbon Dosing Stalls Out

[Tritie]

Hi,

I've managed to kick start and stall my carbon dosing twice now. As soon as I let PO4 drop out even for 12 hours, it ends the bacterial ability to remove nitrates. The film on the glass doesn't reappear after being scraped off, the skimmer stops going crazy and the nitrate starts going back up.

The two times I've kick started the cycle, I once purposely upped Phos to 0.5ppm and once accidentally to 0.8ppm (May was a rough month). A couple days later, I'd do a water change and carbon dosing kicked in.

It has recently stalled out again, but last week I added zoas and LPS to the tank so I don't want to dose phos so high.

Has anyone else had their carbon dosing process stall out due to bottoming PO4? It seems strange that the bacteria would completely stall for weeks on end without phos for 12-24 hours. It seems that the addition of Phos should get it going pretty rapidly again, but no such luck for me.

 

[gbroadbridge]

Hi,

I've managed to kick start and stall my carbon dosing twice now. As soon as I let PO4 drop out even for 12 hours, it ends the bacterial ability to remove nitrates. The film on the glass doesn't reappear after being scraped off, the skimmer stops going crazy and the nitrate starts going back up.

The two times I've kick started the cycle, I once purposely upped Phos to 0.5ppm and once accidentally to 0.8ppm (May was a rough month). A couple days later, I'd do a water change and carbon dosing kicked in.

It has recently stalled out again, but last week I added zoas and LPS to the tank so I don't want to dose phos so high.

Has anyone else had their carbon dosing process stall out due to bottoming PO4? It seems strange that the bacteria would completely stall for weeks on end without phos for 12-24 hours. It seems that the addition of Phos should get it going pretty rapidly again, but no such luck for me.

That's how it works.

The Nitrate reducing bacteria need a source of phospahate and organic carbon in order to do their job.

No phosphate and the process stops.

 

[brandon429]

Are you cycling a tank or trying to alter nutrients in a post cycle tank

 

[00W]

Same. I finally just stopped all together. Was stressing me out. I'll get back to something again later on.
This is not meant to be negative. I just never had much luck with it is all.
I finally just got tired of chasing numbers and let the tank speak for itself.

 

[jda]

You need phosphorous to grow new organic tissue - multiplying bacteria in this case. Bacteria will not multiply very well if you have no phosphorous - there are more sources of phosphorous in a reef tank than just the one the phosphate that you can test for (orthophosphate).

Chances are that you are just dosing too much, the water column shows no po4 on a test kit and in a day, or two, the rock/sand release some phosphate and your po4 is detectable again. If this is the case, then just slow down the OC dosing so that the po4 unbinding from the rock is more linear instead of looking like an EKG graph.

I would not add organic carbon to a reef tank that is not completely stable and predictable. The bacteria will likely outcompete any coral for phosphorous, so you can do some damage if you dose too much. The corals have a bit of an advantage that most hosts can recycle building blocks for their zoox, and such, to hang on for a while, but there will be no growth.

It is OK to have a bit of nitrate in a newer tank. This is what gives fuel to the anaerobic bacteria to start to grow which complete the nitrogen cycle.

 

[Tritie]

That's how it works.

The Nitrate reducing bacteria need a source of phospahate and organic carbon in order to do their job.

No phosphate and the process stops.

Yes. I understand that. But it seems strange that if I were to bottom out for 12 hours, then dose 0.1ppm and maintain 0.03-0.1 over a week that the process doesn't kick back in moe rapidly.

 

[Tritie]

Are you cycling a tank or trying to alter nutrients in a post cycle tank

Post cycle. Tank is 16 months old. Cycled for almost a year, added my fish and just started adding coral.

 

[Tritie]

You need phosphorous to grow new organic tissue - multiplying bacteria in this case. Bacteria will not multiply very well if you have no phosphorous - there are more sources of phosphorous in a reef tank than just the one the phosphate that you can test for (orthophosphate).

Chances are that you are just dosing too much, the water column shows no po4 on a test kit and in a day, or two, the rock/sand release some phosphate and your po4 is detectable again. If this is the case, then just slow down the OC dosing so that the po4 unbinding from the rock is more linear instead of looking like an EKG graph.

I would not add organic carbon to a reef tank that is not completely stable and predictable. The bacteria will likely outcompete any coral for phosphorous, so you can do some damage if you dose too much. The corals have a bit of an advantage that most hosts can recycle building blocks for their zoox, and such, to hang on for a while, but there will be no growth.

It is OK to have a bit of nitrate in a newer tank. This is what gives fuel to the anaerobic bacteria to start to grow which complete the nitrogen cycle.

Whether I dose or not, phos gets eaten up rapidly. If it is 0 for several days, nitrates spiked. I've finally got nitrate spikes down to 10ppm-12ppm per week rather than 25ppm per week.

 

[jda]

What does the po4 level out at if you don't dose or do anything for a few days? it takes the aragonite a bit to unbind po4.

 

[Randy Holmes-Farley Verified Community Expert]

Yes. I understand that. But it seems strange that if I were to bottom out for 12 hours, then dose 0.1ppm and maintain 0.03-0.1 over a week that the process doesn't kick back in moe rapidly.

I do not think it is true that 0.1 ppm phosphate is limiting bacterial growth when dosing organic carbon. Might be coincidence, levels getting lower than you measured, or something else.