PO2 and NO3 suddenly bottomed to 0

[pixelhustler]

I’m dumbfounded, hopefully someone can help me figure this out. I’m providing as much necessary detail as possible so please bear with me.

I had high phosphate and nitrate for a long time, I bought a sulfur denitrator and started dosing lanthanum into a reactor. Phosphate was bound to the live rock, so I started high with lanthanum and slowly started lowering it until it stabilized. I had been running 5-15 nitrates and .02-.05 phosphate consistently (Hanna tests) for over a year now.

Suddenly, phosphate has dropped to 0 and nitrate now dropping under 1ppm. I’m seeing the expected loss of color and STN on my LPS.
- I’m still running my sulfur denitrator with the effluent wide open. Could this be causing the low phosphate? Should I turn it off?
- I’m also running the lanthanum reactor (a reactor that filters the flocculant) but not dosing any more lanthanum. The reactor is full of flocculant. Could this be binding more phosphate? Just turned it off since it’s not necessary.
- I tripled my feeding (2x cubes of frozen) and started feeding pellets 2x/day on my auto feeder, but can barely go over 0.
- Skimmer is running without a cup.
- Redsea reef mat has been running for a long time, I’m turning it off today but this can’t be the culprit.

The only change that perfectly matches this timeline is the plumbing of a 15g AIO tank to the same system. Nutrients started dropping 1 month after installing it. This tank is SUPER low flow as it has jellyfish. I drilled the back AIO compartment as an overflow (picture attached) and I noticed when I stir the bottom of the overflow it smells like decaying matter (not as strong as the sulfur denitrator, but similar). Could this be the culprit? It’s hard to believe that this small system is doing more denitrifying and phosphate reduction than the denitrator + high Lanthanun dosing could handle.

I’m going to have to start dosing nitrate and phosphate, but I’d really like to avoid this. Finding the culprit and going back to my old setup would be easier. Any ideas?

 

[MnFish1]

I’m dumbfounded, hopefully someone can help me figure this out. I’m providing as much necessary detail as possible so please bear with me.

I had high phosphate and nitrate for a long time, I bought a sulfur denitrator and started dosing lanthanum into a reactor. Phosphate was bound to the live rock, so I started high with lanthanum and slowly started lowering it until it stabilized. I had been running 5-15 nitrates and .02-.05 phosphate consistently (Hanna tests) for over a year now.

Suddenly, phosphate has dropped to 0 and nitrate now dropping under 1ppm. I’m seeing the expected loss of color and STN on my LPS.
- I’m still running my sulfur denitrator with the effluent wide open. Could this be causing the low phosphate? Should I turn it off?
- I’m also running the lanthanum reactor (a reactor that filters the flocculant) but not dosing any more lanthanum. The reactor is full of flocculant. Could this be binding more phosphate? Just turned it off since it’s not necessary.
- I tripled my feeding (2x cubes of frozen) and started feeding pellets 2x/day on my auto feeder, but can barely go over 0.
- Skimmer is running without a cup.
- Redsea reef mat has been running for a long time, I’m turning it off today but this can’t be the culprit.

The only change that perfectly matches this timeline is the plumbing of a 15g AIO tank to the same system. Nutrients started dropping 1 month after installing it. This tank is SUPER low flow as it has jellyfish. I drilled the back AIO compartment as an overflow (picture attached) and I noticed when I stir the bottom of the overflow it smells like decaying matter (not as strong as the sulfur denitrator, but similar). Could this be the culprit? It’s hard to believe that this small system is doing more denitrifying and phosphate reduction than the denitrator + high Lanthanun dosing could handle.

I’m going to have to start dosing nitrate and phosphate, but I’d really like to avoid this. Finding the culprit and going back to my old setup would be easier. Any ideas?

1. you might be chasing your tail (no offense). I would not be dosing things that you're actively trying to remove.
2. It's impossible to know exactly what is causing what - but - I can think of at least a couple reasons why your plumbing change could have caused a change (the main reason being because it's temporarily related).
3. I would not dose anything - I would wait for the chemistry in your tank to stabilize. You can feed a little more (which will basically add PO4 and NO3) - you can remove some of your PO4 remover - and I would guess you can turn down your denigrator/

 

[Reefahholic]

Time to stop the Lanthanum dosing and start feeding heavy for a few weeks to make sure this wasn’t a fluke. Turn the skimmer down, pull any socks off, and don’t do any water changes.

If not, it may be time to start dosing PO4 and NO3 back to the system. It sounds like the rock is no longer leaching PO4. Nitrate is less important, but important enough to dose if dropping to zero. If you have bio media, you may need to remove some or all to find balance.

 

[pixelhustler]

1. you might be chasing your tail (no offense). I would not be dosing things that you're actively trying to remove.
2. It's impossible to know exactly what is causing what - but - I can think of at least a couple reasons why your plumbing change could have caused a change (the main reason being because it's temporarily related).
3. I would not dose anything - I would wait for the chemistry in your tank to stabilize. You can feed a little more (which will basically add PO4 and NO3) - you can remove some of your PO4 remover - and I would guess you can turn down your denigrator/

I hear you but the Lanthanum + Denitrator were giving me stable levels for about a year. I didn’t make any changes once dialed in. I stopped lanthanum a few weeks ago and denitrator was running wide open, yet nutrients continued to free fall. In a matter of weeks, things drop to near 0, when my problem was always high nutrients. It’s very strange. What are your theories on the plumbing?

Time to stop the Lanthanum dosing and start feeding heavy for a few weeks to make sure this wasn’t a fluke. Turn the skimmer down, pull any socks off, and don’t do any water changes.

If not, it may be time to start dosing PO4 and NO3 back to the system. It sounds like the rock is no longer leaching PO4. Nitrate is less important, but important enough to dose if dropping to zero. If you have bio media, you may need to remove some or all to find balance.

It’s very strange because I haven’t been dosing for several weeks, I removed the skimmer cup and denitrator has had the effluent fully open which should stop most denitrification. I have been feeding heavy too. Nutrients have continued to drop (nitrate from 1.4 to 0.8, phosphate from .02 to 0).

Unless the new 10g tank that has super low return rate (I’m talking <10GPH) is somehow a nutrient export beast, I don’t know what’s doing it.

 

[pixelhustler]

Time to stop the Lanthanum dosing and start feeding heavy for a few weeks to make sure this wasn’t a fluke. Turn the skimmer down, pull any socks off, and don’t do any water changes.

If not, it may be time to start dosing PO4 and NO3 back to the system. It sounds like the rock is no longer leaching PO4. Nitrate is less important, but important enough to dose if dropping to zero. If you have bio media, you may need to remove some or all to find balance.

Hmmmm I do have a ton of bio media in the sump but I always felt like it didn’t have much of an impact (vs live rock), hence why I added the denitrator and lanthanum reactor. I wonder if something caused the bacterial colony to explode in a matter of months and then it started consuming all my nutrients? I’m not sure if this is even possible. I’ll remove half of it. I’m also trying to be cautious as I don’t want a rebound in the opposite direction.

 

[knockout]

It could also be a sign of your reef maturing and needing less help from you, wouldn't that be nice!

 

[Randy Holmes-Farley]

What is a lanthanum reactor?

If nitrate and phosphate have bottomed out, I'd remove or at least greatly reduce the usage of those.

 

[pixelhustler]

UPDATE - I found the issue:
I turned off my sulfur denitrator completely (before, it was on, with the effluent open all the way).
In 4 days, Nitrate has gone from .08 to 7.2. Phosphate has gone from 0 to .21.

@Randy Holmes-Farley does a sulfur denitrator also lower phosphate? And what could cause such jump in efficiency? I’ve been running this denitrator with stable results for over a year. All of a sudden, it seems to have become much, much more efficient.

What is a lanthanum reactor?

If nitrate and phosphate have bottomed out, I'd remove or at least greatly reduce the usage of those.

I dose lanthanum directly into a RODI style canister with a pleated filter. The pump is very, very low flow so it captures most of the flocculant. I’ve been doing this for about a year as well with stable results.

Could it be possible that the accumulated flocculant is still binding phosphate and, as the flocculant builds up, it exponentially increases the binding? I understood that flocculant was the reaction to the binding itself so once it’s bound the reaction is done. I stopped dosing many weeks ago but the pump was still pushing water through the reactor.

 

[Randy Holmes-Farley]

I don’t see an explanation for the phosphate rise unless the denitrator incorporates calcium carbonate to help maintain alkalinity and pH.

 

[Mikeltee]

All you need is a skimmer. Get rid of the rest of that junk. Prepare for dinos. Most of us make the mistake.

 

[pixelhustler]

All you need is a skimmer. Get rid of the rest of that junk. Prepare for dinos. Most of us make the mistake.

I have a skimmer but it’s not enough. The denitrator and lanthanum are automated and worked flawlessly for the past year.

I don’t see an explanation for the phosphate rise unless the denitrator incorporates calcium carbonate to help maintain alkalinity and pH.

Hmmm I do have a layer of aragonite on top of the sulfur for this reason. Does adding calcium lower phosphate? I’m using Hanna but will test again just in case

 

[blecki]

Prepare for dinos. Most of us make the mistake.

No reason going to zero means you have to get dinos.

If you're feeding heavy and measuring zero it just means it's being used.

 

[Randy Holmes-Farley]

I have a skimmer but it’s not enough. The denitrator and lanthanum are automated and worked flawlessly for the past year.



Hmmm I do have a layer of aragonite on top of the sulfur for this reason. Does adding calcium lower phosphate? I’m using Hanna but will test again just in case

Calcium carbonate can tend to bind phosphate. Perhaps taking that offline stopped that process.