Nitrate problems despite everything I've tried.

[VLSARK]

My aquarium nitrates increase despite everything I am doing. I have a 20 gallon tank with a 20 gallon sump filled with biomedia, 5 gallon bucket filled with pumice with water going through at 50 Gph, 200ml purigen, carbon, 15 oz. Cobalt total nitrate, fluidized sand bed filter v2 bio600f, skimmer eheim hang on back for 100g+ tank, biopellet reactor, deep sand bed with sifting starfish, fluval 306, aquaclear 30, plus overflow/filter box from fluval 32 gallon glued inside 20. I add 100ml instant ocean nitrate reducer weekly, and yesterday added 7.5oz cobalt total nitrate resin. I fed about 20g tilapia yesterday after doing 7g water change with nitrate at 40ppm. Now they are at 60ppm. Despite 7g changes every other day I cannot keep nitrate under control at all. Nothing is eating and I'm surprised stuff hasn't died long ago. Can anyone see what I am doing wrong. The more I try the worse it gets. It's been running for 8+ months and never been this bad.

 

[tbrown]

Are you using RO/DI? Have you tested your source water for nitrates?

 

[Courtney Aldrich]

I think you're feeding too much. 20 grams of tilapia contains about 5 grams of protein, which is about 14% by weight nitrogen. This corresponds to about 730 mg of ammonia that will generate about 2700 mg of nitrate (nitrate weighs 3.7x that of ammonia). Your tank and sump are about 30 gallons or 111 Liters (I subtracted 10 gallons because of your deep sand bed and ceramics and reactors). The tilapia will raise your nitrate levels by 2700 mg/111 L = 24 mg/L = 24 ppm. This is very close to your observed 20 ppm increase.

I would dramatically decrease feeding. I don't think the cobalt total nitrate resin is doing anything either as anion exchange resins cannot work in the presence of high chloride concentrations. These resins are useful in freshwater, but not saltwater despite the manufacturer claims.

 

[Cwentz758]

I would also suggest finding a simpler way to your filtration, you’ve got a lot going on. I see two canister filters which can turn into a nitrate bucket.

Feed less also.

 

[CanuckReefer]

Tilapia? Stop with that garbage feed first off....if it kills you quick, it will kill the wee ones faster....
As @Cwentz758 mentions you have a heck of a lot going on here in a system of this size, you are creating nitrates exponentially.

 

[JosephM]

Have you tried vodka dosing or something such as vibrant or MB7. Those help biological diversity and can help lower nitrates

 

[Ghost25]

Wow that is a lot of stuff and a lot of food. 20g of food in one day!? How much live rock is in the tank?

If it was me I would feed way less, ditch the DSB, do a few water 20% water changes over a week or two and honestly slowly remove everything except the skimmer, assuming you have enough live rock. Clearly all this stuff is not helping and some if could be making things worse.

 

[Jekyl]

Welcome to R2R! There's a whole lot going on there. Have you had the water tested elsewhere? Api kits are known for being wrong. Should be able to run just the skimmer and chaeto to combat nitrates. Some people it does too good of a job. Using RoDi water?

 

[Jekyl]

Also third that feeding is way too much. 1/4 cube of mysis or other frozen would be enough. If even that much.

 

[CanuckReefer]

Welcome to R2R! There's a whole lot going on there. Have you had the water tested elsewhere? Api kits are known for being wrong. Should be able to run just the skimmer and chaeto to combat nitrates. Some people it does too good of a job. Using RoDi water?

I'm just seeing WAY too much going on via the pics and descriptions for a 20g setup Jekyl....agreed? This could be much simpler imo....

 

[Rjmul]

I think you're feeding too much. 20 grams of tilapia contains about 5 grams of protein, which is about 14% by weight nitrogen. This corresponds to about 730 mg of ammonia that will generate about 2700 mg of nitrate (nitrate weighs 3.7x that of ammonia). Your tank and sump are about 30 gallons or 111 Liters (I subtracted 10 gallons because of your deep sand bed and ceramics and reactors). The tilapia will raise your nitrate levels by 2700 mg/111 L = 24 mg/L = 24 ppm. This is very close to your observed 20 ppm increase.

I would dramatically decrease feeding. I don't think the cobalt total nitrate resin is doing anything either as anion exchange resins cannot work in the presence of high chloride concentrations. These resins are useful in freshwater, but not saltwater despite the manufacturer claims.

Good math.

 

[Rjmul]

I just use nopox and skimmer.

 

[CanuckReefer]

My aquarium nitrates increase despite everything I am doing. I have a 20 gallon tank with a 20 gallon sump filled with biomedia, 5 gallon bucket filled with pumice with water going through at 50 Gph, 200ml purigen, carbon, 15 oz. Cobalt total nitrate, fluidized sand bed filter v2 bio600f, skimmer eheim hang on back for 100g+ tank, biopellet reactor, deep sand bed with sifting starfish, fluval 306, aquaclear 30, plus overflow/filter box from fluval 32 gallon glued inside 20. I add 100ml instant ocean nitrate reducer weekly, and yesterday added 7.5oz cobalt total nitrate resin. I fed about 20g tilapia yesterday after doing 7g water change with nitrate at 40ppm. Now they are at 60ppm. Despite 7g changes every other day I cannot keep nitrate under control at all. Nothing is eating and I'm surprised stuff hasn't died long ago. Can anyone see what I am doing wrong. The more I try the worse it gets. It's been running for 8+ months and never been this bad.

Ok, let's start with what is in your tank.... Live Rock or no? What is the complete species list. That will help get all of us on the case....

 

[Jekyl]

First thing I would get some salifert kits and rodi if not already using it. Otherwise somewhere in your system has turned into a nitrate factory if the numbers are right. I'd start by eliminating a lot of what's going on. The extra bucket and all of the blocks going on may just be trapping detritus. With just the protein skimmer, chaeto on an opposite light schedule and proper feeding and cleaning, nitrates shouldn't be an issue. Next water change use a turkey baister and blow off your rock work and do a good vacuuming of the sand

 

[vetteguy53081]

Lets talk test kits. You may be getting false readings which API is notorious for. I would get a second opinion, taking a water sample to a trusted LFS that does NOT use API kit and see what they come up with and to compare with your readings

 

[DaneGer21]

What livestock in your tank are you feeding that much?

 

[CanuckReefer]

I just use nopox and skimmer.

Meaning no canister? Good for you, if so....LR, Skimmer periodically here (on and off with my lights along with a small UV) , a polishing powerhead...thats it.

 

[VLSARK]

I think you're feeding too much. 20 grams of tilapia contains about 5 grams of protein, which is about 14% by weight nitrogen. This corresponds to about 730 mg of ammonia that will generate about 2700 mg of nitrate (nitrate weighs 3.7x that of ammonia). Your tank and sump are about 30 gallons or 111 Liters (I subtracted 10 gallons because of your deep sand bed and ceramics and reactors). The tilapia will raise your nitrate levels by 2700 mg/111 L = 24 mg/L = 24 ppm. This is very close to your observed 20 ppm increase.

I would dramatically decrease feeding. I don't think the cobalt total nitrate resin is doing anything either as anion exchange resins cannot work in the presence of high chloride concentrations. These resins are useful in freshwater, but not saltwater despite the manufacturer claims.

I did kind of think the total nitrate was bs, but it says can be regenerated with bleach. It doesn't seem to help at all though. I did not feed/do anything for 4 days prior to this and with daily testing nitrate continued to increase. Problem is I have 2x astropyga radiata and they eat like pigs. Usually i feed 2 sheets of seaweed and 6cm^3 tilapia( I dont usually weigh it), just to keep them from eating everything else. I am unwilling to get rid of any animals, but am definitely willing to try and build new filtration. I am thinking anaerobic recirculating fluidized sand bed and maybe sulfur reactor. Is there anything you can think of I can do to enhance denitrification?

 

[VLSARK]

Are you using RO/DI? Have you tested your source water for nitrates?

Yes. 5ppm in removed by my ro/di unit.

 

[VLSARK]

I would also suggest finding a simpler way to your filtration, you’ve got a lot going on. I see two canister filters which can turn into a nitrate bucket.

Feed less also.

I change media weekly.