Getting nitrates under control...the saga continues

[Ciwyn]

So I have been battling a nutrient problem in my tank basically since I cycled it 2.5 years ago. After my cycle completed my nitrates were at 50-60. Initially I was reading PO4 in the tank about .08. About a month or so later the PO4 bottomed out and would stay there unless I dosed phosphate into the tank (which I am still doing currently). I also had a pretty good cyano breakout for several months shortly after the cycle.

The cyano disappeared but my nitrates continued to be high. An ICP test I did 1.5 years ago had them at ~80 and phosphate at essentially zero. The recommendation from ATI was actually to add phosphorus to the aquarium as that was basically non existent in the tank as well.

So now to present day. I have lost most of my corals and my sand bed always looks dingy with some kind of algae. I set up a DIY denitrator from the DIY section on this forum hoping that would help. It hasn’t. I am dosing 34 ml of vodka into the denitrator but the NO3 coming out hasn’t changed.

Now to finally get to the bottom of this and hopefully get my aquarium looking good this year I did another ICP test to see what my nitrates were doing. Well they are currently 237. Way to high. So I have started to get much more aggressive with water changes to start bringing them down. This is a 300 gallon aquarium so doing a very large water change would be rather difficult. I have a 35 gallon brute container for saltwater mixing. My water change system will take about 25 gallons out of the sump then refill it with fresh saltwater. I plan on doing this daily whenever I am home.

My questions for those with more knowledge than myself would be:
Since the denitrator doesn’t seem to be doing any good should I just take it offline and dose vodka directly to the tank?
Is 34 ml of vodka daily too much for a 300 gallon tank with nitrates that high?
What are my potential sources for this high nitrate? I have about a dozen fish in the tank only one yellow tang and one fox face the others are relatively small fish (clowns, fire fish, blenny, small wrasses). I feed about the equivalent of a cube of mysis shrimp daily. I run a large skimmer and have a 10 gallon refugium. The tank has been running for about 2.5 years so any nutrients from my rock should be spent.
Finally, what could be causing this weird nutrient imbalance? If I don’t dose phosphate it will bottom out at 0. Nitrate just appears to keep climbing no matter what.

Of course I can share the ICP test results if that is helpful as well.

Thanks

 

[Ippyroy]

The water changes should help lower the NO3. I would feed dry food multiple times a day. Try running the fuge every other day for just a few hours. I ran mine for 45 minutes on and 30 off for a few months. The chaeto grew fine and my nutrients levelled out and stayed stable. If it was my tank I would only run the fuge for 2 hours a day every other day. If you have corrals feeding reef roids will raise your PO4. Do you have any algae growing in the tank?

 

[arking_mark]

My understanding of Nitrates revolves around import vs export. Import comes from food and biological processes. Export comes from mechanical and biological filtration.

What are you doing for export? If you were relying on a denitrator setup that wasn't really working (I don't have experience with these) then you may not have had much export.

In my opinion good exporters are bacteria and macro algae.

Export helpers are water changes and skimmers.

Avoiders are filters that remove stuff before it becomes nitrate such as mechanical filters and some media.

Each method has a ton of interesting techniques to maximize benefits.

Since you already have a nitrate problem, I would focus on water changes, increasing your good bacteria, and turbo charging your refugium.

As you mentioned, it's hard to do water changes on a 300gal tank. You may want to invest in an AWC.

 

[Dan_P]

So I have been battling a nutrient problem in my tank basically since I cycled it 2.5 years ago. After my cycle completed my nitrates were at 50-60. Initially I was reading PO4 in the tank about .08. About a month or so later the PO4 bottomed out and would stay there unless I dosed phosphate into the tank (which I am still doing currently). I also had a pretty good cyano breakout for several months shortly after the cycle.

The cyano disappeared but my nitrates continued to be high. An ICP test I did 1.5 years ago had them at ~80 and phosphate at essentially zero. The recommendation from ATI was actually to add phosphorus to the aquarium as that was basically non existent in the tank as well.

So now to present day. I have lost most of my corals and my sand bed always looks dingy with some kind of algae. I set up a DIY denitrator from the DIY section on this forum hoping that would help. It hasn’t. I am dosing 34 ml of vodka into the denitrator but the NO3 coming out hasn’t changed.

Now to finally get to the bottom of this and hopefully get my aquarium looking good this year I did another ICP test to see what my nitrates were doing. Well they are currently 237. Way to high. So I have started to get much more aggressive with water changes to start bringing them down. This is a 300 gallon aquarium so doing a very large water change would be rather difficult. I have a 35 gallon brute container for saltwater mixing. My water change system will take about 25 gallons out of the sump then refill it with fresh saltwater. I plan on doing this daily whenever I am home.

My questions for those with more knowledge than myself would be:
Since the denitrator doesn’t seem to be doing any good should I just take it offline and dose vodka directly to the tank?
Is 34 ml of vodka daily too much for a 300 gallon tank with nitrates that high?
What are my potential sources for this high nitrate? I have about a dozen fish in the tank only one yellow tang and one fox face the others are relatively small fish (clowns, fire fish, blenny, small wrasses). I feed about the equivalent of a cube of mysis shrimp daily. I run a large skimmer and have a 10 gallon refugium. The tank has been running for about 2.5 years so any nutrients from my rock should be spent.
Finally, what could be causing this weird nutrient imbalance? If I don’t dose phosphate it will bottom out at 0. Nitrate just appears to keep climbing no matter what.

Of course I can share the ICP test results if that is helpful as well.

Thanks

How long was the denitrator working?

Was there 0 ppm nitrate in the water leaving the denitrator?

What is in the refugium?

 

[Ciwyn]

My understanding of Nitrates revolves around import vs export. Import comes from food and biological processes. Export comes from mechanical and biological filtration.

What are you doing for export? If you were relying on a denitrator setup that wasn't really working (I don't have experience with these) then you may not have had much export.

In my opinion good exporters are bacteria and macro algae.

Export helpers are water changes and skimmers.

Avoiders are filters that remove stuff before it becomes nitrate such as mechanical filters and some media.

Each method has a ton of interesting techniques to maximize benefits.

Since you already have a nitrate problem, I would focus on water changes, increasing your good bacteria, and turbo charging your refugium.

As you mentioned, it's hard to do water changes on a 300gal tank. You may want to invest in an AWC.

I have a water change setup that is semi automatic. I turn off my return pump and push a button on my controller and it will change ~25 gallons of water for me. The trick is constantly making more fresh saltwater. I can do the 25 gallon change every day that I'm home though. Which should changing out about 300 gallons a month.

Poor Man's Nutrients Control - Donovan's Nitrate Destroyer

Hello fellow reefers!. I have been in the hobby for more than 3 years, the first 2 years was tough. Cyno, diatom, nuisance algae, high NO3 (120ppm at one time) and ich/velvet. I have tried several nutrient control method (poor man, so most of it were DIY project). GFO, water fall scrubber...

www.reef2reef.com

This is the denitrator setup I am using. It basically puts the carbon dosing into an anerobic environment and is supposed to be quite efficient at eliminating nitrate. This does not appear to be the case for my setup unfortunately. That is why I'm considering just doing carbon dosing directly into my aquarium.

So my aquarium has been running for about 2.5 years. I have 200+ pounds of mostly pukani rock in it. There should be a large nitrifying bacteria population in the rock but I have no way of knowing how to test for that.

I also have a 10 gallon tank as a refugium with chaeto growing in it. The chaeto used to grow quite rapidly but appears to have slowed down as of late. (Again this is probably somehow related but I'm not sure why).

Thanks for the reply. I don't expect this to be solved by one single post but we have some starting ground to hopefully find a solution.

 

[ChrisOFL]

It sounds like your bacteria are starved for phosphate and could explain why the denitrator is not working and your nitrates have consistently increased. You may need to dose more phosphate but do so more periodically rather than in one large dose. A sulfur denitrator works differently than the one you built and would be more effective in reducing nitrates for your situation because you are phosphate limited.

 

[arking_mark]

I have a water change setup that is semi automatic. I turn off my return pump and push a button on my controller and it will change ~25 gallons of water for me. The trick is constantly making more fresh saltwater. I can do the 25 gallon change every day that I'm home though. Which should changing out about 300 gallons a month.

Poor Man's Nutrients Control - Donovan's Nitrate Destroyer

Hello fellow reefers!. I have been in the hobby for more than 3 years, the first 2 years was tough. Cyno, diatom, nuisance algae, high NO3 (120ppm at one time) and ich/velvet. I have tried several nutrient control method (poor man, so most of it were DIY project). GFO, water fall scrubber...

www.reef2reef.com

This is the denitrator setup I am using. It basically puts the carbon dosing into an anerobic environment and is supposed to be quite efficient at eliminating nitrate. This does not appear to be the case for my setup unfortunately. That is why I'm considering just doing carbon dosing directly into my aquarium.

So my aquarium has been running for about 2.5 years. I have 200+ pounds of mostly pukani rock in it. There should be a large nitrifying bacteria population in the rock but I have no way of knowing how to test for that.

I also have a 10 gallon tank as a refugium with chaeto growing in it. The chaeto used to grow quite rapidly but appears to have slowed down as of late. (Again this is probably somehow related but I'm not sure why).

Thanks for the reply. I don't expect this to be solved by one single post but we have some starting ground to hopefully find a solution.

I'm far from an expert and am always learning new things, but I think your gut is right. I would probably do 2 x 25gal water changes each week for the next 3 weeks. Ditch the DIY denitrator and dose carbon directly to tank and monitor changes.

 

[Ciwyn]

How long was the denitrator working?

Was there 0 ppm nitrate in the water leaving the denitrator?

What is in the refugium?

I set the denitrator up in December. The water coming out of it is not 0 nitrate. I believe it is the same as the tank water. When the nitrate test kit reads that high all I know is that my nitrates are way higher than I want them. That's why the numeric value of the ICP test was so helpful.

 

[Ciwyn]

It sounds like your bacteria are starved for phosphate and could explain why the denitrator is not working and your nitrates have consistently increased. You may need to dose more phosphate but do so more periodically rather than in one large dose. A sulfur denitrator works differently than the one you built and would be more effective in reducing nitrates for your situation because you are phosphate limited.

Interesting. I have found this phosphate issue very odd as most people seem to battle trying to get rid of phosphate. I just wonder what in my tank is causing phosphate and phosphorus to be so limited?

I dose phosphate daily. I'll have to dig up the exact chemical I'm using (it's one of the ones Randy Holmes Farley suggested to someone else). I dose about .5 ml every day and that seems to keep my phosphate at .02-.08. So that is actually fairly consistent now.

I will have to take a look at the sulfur denitrator. Do you think it's possible to convert the one a built into one?

 

[Rmckoy]

My understanding of nutrients with one sitting at 0
It’s limited and will not decrease without bringing the other up to balance .
most methods work by reducing both nitrates and phosphates .
if it can’t decrease one , the other will not drop .

increase phosphates by dosing and nitrates will gradually decrease .
My 230 was opposite . High phosphates and zero nitrates .

dosing to increase nitrates 1ppm per day for 5 days brought it up to 5ppm

tested the phosphates a week later without water changes and phosphates were 0.035ppm from 0.57

 

[ChrisOFL]

Interesting. I have found this phosphate issue very odd as most people seem to battle trying to get rid of phosphate. I just wonder what in my tank is causing phosphate and phosphorus to be so limited?

I dose phosphate daily. I'll have to dig up the exact chemical I'm using (it's one of the ones Randy Holmes Farley suggested to someone else). I dose about .5 ml every day and that seems to keep my phosphate at .02-.08. So that is actually fairly consistent now.

I will have to take a look at the sulfur denitrator. Do you think it's possible to convert the one a built into one?

DIY – Sulfur Reactor - Reefkeeping.com

These are the instructions on how to build one so you will have to see if you can convert yours.

So the reason I think people tend to have phosphate issues more often is because the food they feed has high phosphate content. Pellet food tends to have a much higher amount than frozen food and a lot of people feed pellets.

 

[Rmckoy]

Can a denitrifying reactor be made from a phosban reactor ?
jait swapping out media ?

 

[Ciwyn]

My understanding of nutrients with one sitting at 0
It’s limited and will not decrease without bringing the other up to balance .
most methods work by reducing both nitrates and phosphates .
if it can’t decrease one , the other will not drop .

increase phosphates by dosing and nitrates will gradually decrease .
My 230 was opposite . High phosphates and zero nitrates .

dosing to increase nitrates 1ppm per day for 5 days brought it up to 5ppm

tested the phosphates a week later without water changes and phosphates were 0.035ppm from 0.57

I had a similar mindset to what you’ve said. That’s why I started dosing phosphate. I tried it first about 2 years ago and I may have been a little too aggressive with dosing the phosphate. It seemed to make all my coral very mad. So I backed off and my phosphate bottomed out again.

I started dosing phosphate more conservatively this time and have kept the phosphate stable between .02 and .1. I’m not sure if slowly increasing the phosphate higher would help with the nitrates or not? I’m slightly afraid to do so. I also don’t know what level of phosphate would be high enough to do so. If I were to match the redfield ratio that would mean a very significant increase in phosphate.

 

[Ciwyn]

Can a denitrifying reactor be made from a phosban reactor ?
jait swapping out media ?

I did a quick search and yes that seems possible although the one thread I read on this (from 2007) said you would need to daisy chain several together to make sure all the system.

Which also makes me wonder if that is part of the problem I’m having with my denitrator.

 

[Twoddler]

I,m going through the same problem as you, I have a 220 gal tank. High NO3 100+ and low PO4 0.06 ppm.
I can manage 20gal water change every 3 days and have been doing for the last month with no significant change.
I have a very good lfs, they recommend I ramp up my fudge from 8hrs to 15hrs and monitor P04, if P04 was to bottom out I would have to dose.

A week later N03 sits around 64ppm ( Redsea pro ) P04 0.04ppm ( Hannah ) I,m feeding a mix of frozen and pellet, also reef roids. Still water changing but a least I'm seeing an improvement

 

[Ciwyn]

I,m going through the same problem as you, I have a 220 gal tank. High NO3 100+ and low PO4 0.06 ppm.
I can manage 20gal water change every 3 days and have been doing for the last month with no significant change.
I have a very good lfs, they recommend I ramp up my fudge from 8hrs to 15hrs and monitor P04, if P04 was to bottom out I would have to dose.

A week later N03 sits around 64ppm ( Redsea pro ) P04 0.04ppm ( Hannah ) I,m feeding a mix of frozen and pellet, also reef roids. Still water changing but a least I'm seeing an improvement

That PO4 seems like it's in the ideal range. Also sounds like the water changes are working if your NO3 has come down like that.

I tried a nearly 100 gallon water change last year and it looked like my nitrates hadn't even budged after it. It was rather frustrating.

 

[Aqua Man]

lost most of my corals and my sand bed always looks dingy with some kind of algae

So there is still coral and fish surviving?!!

That number seems almost impossible, 237 ppm Nitrates?!! Maybe get another company to do ICP?

Do you have a deep sand bed? Are your rocks also growing major algae?

 

[Ciwyn]

So there is still coral and fish surviving?!!

That number seems almost impossible, 237 ppm Nitrates?!! Maybe get another company to do ICP?

Do you have a deep sand bed? Are your rocks also growing major algae?

Zoas and mushrooms and ricordia along with a hammer are hanging on. Fish are doing fine actually.

It may not be that exact number but I'm fairly sure they are high. This confirms it and I know I need to set a course to correct it. Also my nitrates have always been high in this tank from the start.

 

[Ciwyn]

Also something "clever" (may actually be dumb) I will do with my water changes to let me exchange a little more water; is mix my saltwater to a bit higher salinity. Something like 1.030 then use my top off water during the change to dilute it a bit.

Since my water changes are only about 10% it can't throw my salinity off by too much.

 

[Mike in CT]

I have a hunch your nitrates are not as high as the tests say. When I was unable to do water changes for a while and my nitrates went above 100, the only corals that survived were the softies, every thing else slowly deteriorated and my hammer rather quickly.