Can't get Nitrates down.

[Matt Winstead]

Took over my 2 year 250gal tank from previous maintenance tech. Since then I've gotten all the parameters in line except nitrates aren't coming down.
I've done six 40 gallon water changes in the last 10 days.
Previous numbers Today's numbers
Salinity 20ppm. 32.5ppm
Phosphates 1.94. 0.4
PH 7.9-8.2. Same
Alkalinity 12.0. 8.4
Calcium 200. 480
Magnesium 800. 1520
Nitrate 100. 32

this is my first time maintaining my tank. I'm absorbing all the info I can.
I'm running carbon. GFO. Red Sea NoPox. Red Sea Coral Food. Refugium Sea Lettuce.

 

[1ByLand2BySea]

It seems you brought the numbers down quite a bit and the water changes have worked. But It is pretty fast and drastic in 10 days and some corals and bio-fauna may not react to it well.
What kind of coral do you keep in your tank?
What test kits do you use to measure?
What is your target NO3 and PO4?

 

[Matt Winstead]

It seems you brought the numbers down quite a bit and the water changes have worked. But It is pretty fast and drastic in 10 days and some corals and bio-fauna may not react to it well.
What kind of coral do you keep in your tank?
What test kits do you use to measure?
What is your target NO3 and PO4?

LPS tank. Anytime I bought SPS they all died. I'm trying to hit 1.0 or less and .05 or less.

 

[Thespammailaccount]

In order to reduce nitrate via water change you will have to change 50% of water at once to reduce nitrate in half but that will be short lived until you figure out where the nitrates are coming from

 

[pdxmonkeyboy]

When using nopox you need phos to reduce nitrates, i agreee with above. That is a big drop, let it be for awhile

 

[Bfragale]

Looks like numbers are getting closer. One thing you can try is to run refugium lights longer, it may help reduce no3.

For me no3 was a slow process to correct. Took about 4 months to go from 50 pm to 10ppm. All I did was run refugium lights longer and 15% water changes weekly.

 

[1ByLand2BySea]

LPS tank. Anytime I bought SPS they all died. I'm trying to hit 1.0 or less and .05 or less.

Clearly SPS won't survive in the water with your original numbers. On the other hand you have to find out why your numbers were that high to start with.
Was it as a result of no maintenance or poor maintenance?
You have to slow down now and get a hang of the rate that the NO3 and PO4 increased in your tank and you might come up with an appropriate solution to address.
Please pay attention with the NO3:O4 ratio in your tank as there should be a balance there. Too high or low of one in compare to other could cause issues.
Please also look up on Ultra Low nutrient tanks and how to manage it. It seems thats what you are shooting for and some of your LPS's may not like it. Even a lot of SPS tank holders don't keep such a low NO3 numbers in their tanks.

 

[jccaclimber]

Say your system has 250 actual gallons of water. A bit less for air, substrate, rocks, etc. a bit more for the sump. A 40 gallon water change is 16%, so if you nitrates start at 100, then they would be 100*(1-0.16)^n afterwards, with n being the number of water changes you did.
So, 100>84>71>59>50>42>35. So, yes, 32 sounds about right.
Assuming you have sand in there, I’m going to guess it’s really dirty. You can test this by picking up a handful and releasing it back into the tank. If there is a cloud you fail, if things look normal after 5 seconds you pass. I mention this because if there is a large amount of organic matter in the sand it will keep pushing your nitrates up. Digging through the sand when doing water changes is the easy fix for this.

The bigger concern is phosphate. There will likely be a ton of it bound into the rocks, so if you want lower levels you may need to use some GFO to gradually absorb it as it leaches back out.

The good news is that I’ve seen a lot of really nice SPS tanks with 20 PPM NO3. Personally I like 5 PPM as a target. Bad things happen if you run short (ie a hard 0) and the majority of even acros out there will have no issues at 10 PPM. Running at 1 PPM is difficult if your tank runs an excess, and leaves you at risk of pale coral or STN if your system starts consuming it faster.

Assuming those values were correct, the Calcium and Magnesium levels alone would kill SPS faster than the nitrate and phosphate levels IMO.

 

[Matt Winstead]

In order to reduce nitrate via water change you will have to change 50% of water at once to reduce nitrate in half but that will be short lived until you figure out where the nitrates are coming from

Well I will post pics of the fish. Aren't fish pretty much the only reason a tank has nitrates from detritus ? I'll send pics of my fish when the lights come on.

 

[Randy Holmes-Farley Verified Community Expert]

I would not agonize over 32 ppm nitrate, if accurate. It is certainly not an emergency. Many fine tanks have much higher nitrate.

I'd just develop a long term nitrate reduction plan.

 

[Cory]

Describe your refugium. What kind of lights for it? How much ulva do you have in it?

 

[Matt Winstead]

Attached shows my fish stock. dang nítrate producers lol.

 

[ReeferWarrant]

I started doing Vodka dosing with my skimmer, additionally did a 30% and two 10% changes in a matter of 3 days. I went from ~40ppm to ~10ppm after 2 weeks. It might be worth looking into.

 

[jccaclimber]

As a minor point, fish do not produce nitrate out of thin air. They only process the nitrate in the food that you add to the tank. Change the amount of food without changing the fish and the nitrate input will change. Same with export methods.

 

[jccaclimber]

(Edit on the above post). Process nitrogen in the food.

 

[Fishnut]

I wouldn’t be too concerned with those numbers if keeping LPS and soft corals. I like to keep it simple and just stock corals that can handle it. My tank averages 80+ Nitrate and all is well. I would not expect SPS to survive in this tank. Just my 2cents

 

[Pistondog]

Took over my 2 year 250gal tank from previous maintenance tech. Since then I've gotten all the parameters in line except nitrates aren't coming down.
I've done six 40 gallon water changes in the last 10 days.
Previous numbers Today's numbers
Salinity 20ppm. 32.5ppm
Phosphates 1.94. 0.4
PH 7.9-8.2. Same
Alkalinity 12.0. 8.4
Calcium 200. 480
Magnesium 800. 1520
Nitrate 100. 32

this is my first time maintaining my tank. I'm absorbing all the info I can.
I'm running carbon. GFO. Red Sea NoPox. Red Sea Coral Food. Refugium Sea Lettuce.

Is the sea lettuce growing, or do you need to improve this?

 

[Matt Winstead]

Regarding food amount I'm feeling two of these blocks of frozen seafood mix per day and a sheet of seaweed per two days.

 

[Matt Winstead]

Is the sea lettuce growing, or do you need to improve this?

Growing but really slow. I feed it to my fish. I wish it grew faster. Every time I tried Chaeto it died.

 

[Matt Winstead]

I started doing Vodka dosing with my skimmer, additionally did a 30% and two 10% changes in a matter of 3 days. I went from ~40ppm to ~10ppm after 2 weeks. It might be worth looking into.

Thank you. Do you continue with the vodka? How much vodka per 100 gal?