Nitrates

[cwwallis]

So I have had my 90 gallon up for a year give or take a few minutes and sence day one my nitrates have been high. While this has not caused me any "major" issues I'm not sure of the root cause or the fix to the the problem. I have tried gfo, no pox, water changes it goes down for a little while then right back up. It's the weirdest thing my lfs has ever seen. I get my water tested weekly and I am affectionately named his problem child because of this tank. Anybody got any insite. The first that's gonna be said is over feeding I only feed every other day now and no dosing of any kind except phyto.

 

[splunty]

You're not wrong. Feeding is how nitrates are introduced to the tank. Dosing phytos (aka food) will cause your nitrates to go up as well, especially if they aren't consumed and break down in the water column or filtration.

Do you have mechanical filtration? How often do you change the filters?

Do you have a protein skimmer? How often are you harvesting that?

What are your nitrates/Phosphates readings right now?

FYI GFO will not work as a nitrate export. Algae (or macroalgae) will though.

 

[ChrisfromBrick]

gfo is used for phosphate removal. What other equipment do you have running?

 

[cwwallis]

gfo is used for phosphate removal. What other equipment do you have running?

I have a skimmer and filter floss the gfo in my reactor and that's it

 

[cwwallis]

You're not wrong. Feeding is how nitrates are introduced to the tank. Dosing phytos (aka food) will cause your nitrates to go up as well, especially if they aren't consumed and break down in the water column or filtration.

Do you have mechanical filtration? How often do you change the filters?

Do you have a protein skimmer? How often are you harvesting that?

What are your nitrates/Phosphates readings right now?

FYI GFO will not work as a nitrate export. Algae (or macroalgae) will though.

My nitrates are at around 50 phos is at zero. Filters are skimmer and filter floss

 

[splunty]

I would remove the GFO at lesat until you have measurable Phosphates. Zero Phosphates is not good and may lead to a dino explosion. Artificially keeping Phosphates at zero can also cause nitrates to climb as you're starving (perhaps nuisance) algae and other common nutrient exports that need both nutrients to survive. I think most of us aim for a range between .03 and 1.0 for Phosphates. Higher is better than lower.

Once you've got measurable Phosphates, and keep them measurable, you should see things balance out a bit more. You will probably see more algae growth, which is normal. At that point you can perform one or two large water changes to lower the nitrate levels. Measure nitrates before the changes, then a couple of days after, and you can determine how fast they are climbing.

If that rate of climb can be managed with water changes, you're golden. If it's climbing faster than you are comfortable controlling with water changes, revisit your feeding habits, consider a refugium, or consider other methods such as vodka dosing.

But I would really recommend getting Phosphates into range. Randy Holmes-Farley discusses optimal nutrient levels here:

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There are many different attributes of the aquarium...

www.reef2reef.com

I hope this helps a bit. Happy reefing is all about getting your nutrients balanced and stable. Don't try any quick fixes or dosing until you're sure the simple things (balanced nutrients, water changes) aren't going to do the trick.

Good luck!

 

[splunty]

Once you've got measurable Phosphates, and keep them measurable, you should see things balance out a bit more. You will probably see more algae growth, which is normal. At that point you can perform one or two large water changes to lower the nitrate levels. Measure nitrates before the changes, then a couple of days after, and you can determine how fast they are climbing.

Just to follow up to myself.

Nitrates are primarily suspended in the water column. So a 20% water change should lower nitrates approximately 20%.

Phosphates are primarily suspended in the rock surfaces. So a 20% water change should effectively do nothing to your phosphate measurements.

This is a big reason I am pointing out your zero phosphate reading. If you are reading zero, and running GFO, that means you're (probably? definitely?) leaching Phosphates out of your rocks. That also means it may take a considerable amount of time before Phosphates start climbing back up and staying at good levels. Any you add from here, for a while, will just be absorbed into the rocks again.

Good luck!