What level is the ideal level for nitrate in saltwater aquarium ?

Mr.cj · Mar 25, 2018

Hi guys!
I have fluval 13.5 gallons saltwater aquarium recently i had brown algea problem in the tank so i tested my water and noticed that my phosphate and nitrate were high
Phos: 0.19 , Nitrate : 40 so i did two (40%) massive water change and right now my phosphate is 0 and nitrate is 10 ppm. i asked from two different fish store about the ideal level for nitrate and they gave two completly different answers.
One of them told me the nitrate needs to be close to zero and the other one said below 20 ppm is safe. So im kinda lost and i dont want to get the algea problem again. Does anyone know for sure ?
Thank you.

SashimiTurtle · Mar 25, 2018

First thing to get out of the way, what are your goals for your tank? Is this going to be a fish only with live rock(FOWLR) or a reef? If going the reef route, will you be keeping softies, LPS or trying your hand at some SPS.

The nutrient levels can differ for each one of these systems. What may work for one, won't for the other and vise versa. That being said, 5-10ppm nitrate is a good number to shoot for, and .03-.08 phosphate, but really try and aim for the lower end of the phosphates.

SashimiTurtle · Mar 25, 2018

Mr.cj said:
I have fluval 13.5 gallons saltwater aquarium

i did two (40%) massive water change

Sorry, I just had to chuckle at this a little bit. I have a little IM 14g nano myself, and a "massive" 50% water change is literally one five gallon bucket.

Reef Jeff · Mar 25, 2018

You will get many conflicting answers to this. There are people running beautiful SPS tanks and mixed reefs, both with high nitrates and phosphates. What your two local fish stores told you are both correct answers. For NO3, anything between detectable levels and 20 ppm+ is okay. I have a mixed Reef and I prefer 1-2 ppm NO3 and .05-.08 ppm PO4 using Red Sea test kits.

Here’s what is most important: neither level should be zero as measured with a high quality test kit. Zero levels cause problems unless you are running an ULNS and using nutrient additives to feed the corals. As for high levels, phosphate is the critical one as it causes undesirable algae and issues with coral growth when too high. Some say keep it low .02-.03. Others say a bit higher .03-.08. Once you hit .1 ppm and above you may start seeing issues. These are generalities because one test kit may read .12 and your tank has no issues while another’s test kit may read .05 and they have algae problems. There are many factors affecting what works beside just these test results.

I find my LPS corals like .05-.08 PO4 the best and they show the best polyp extension and color at that level. That level causes no problems with my SPS either. Below .03 I start to see colors pale. There are no magic numbers, but based on my experience these are good guidelines to shoot for. Hope that helps.

crayon · Mar 25, 2018

This is a conversation I have with all the experts I run across. Especially at MACNA when I can talk to the manufacturer’s reps and those who make and sell nitrate reducing products and food.
At the end of the day, it depends on what corals you are keeping as well. If they acclimate to the level of nutrients in your tank, then let it be. The key is consistency. In a small tank that’s hard to acehive but once you find a way to keep nitrates at a consistent level and the corals are happy, try and keep it there.
Fauna Marin told me nitrates under 30 is perfect for LPS and softies. Phosphates at 0.05 max.
My corals are happiest at these levels so this is what I strive for. Nitrates are food and the corals need food.

ontop27 · Mar 25, 2018

Personally i talked to a really nice store in my area and i told him about lps problems i was having. I was dosing nitrate which amounted to 5 ppm. He told me to bump it to 20 ppm. Without changing anything else, blastos that were clear came back, scolys that were blah came back, and now my acans are doing better as well.

SashimiTurtle · Mar 25, 2018

ontop27 said:
Personally i talked to a really nice store in my area and i told him about lps problems i was having. I was dosing nitrate which amounted to 5 ppm. He told me to bump it to 20 ppm. Without changing anything else, blastos that were clear came back, scolys that were blah came back, and now my acans are doing better as well.

My tank has very low nitrates... but very happy LPS. I feed a bunch of phyto and oysterfeast daily. 1/2oz of phyto a day for a 35g tank. I also grow chaeto like weeds in the sump to keep nitrates ultra low. High nutrients, low nitrates.

If you're going to have low nitrates, you gotta feed your corals.

Reef Jeff · Mar 25, 2018

I agree with Robin. I would not dose Nitrates to 20 ppm. I would keep them lower and use real coral food to target feed corals. Results will be better like Robin’s picture shows.

By the same token, if my Nitrates ran 20 ppm and they would not come down and everything was happy, I would leave levels alone.

paul barker · Apr 1, 2018

Mr.cj said:
Hi guys!
I have fluval 13.5 gallons saltwater aquarium recently i had brown algea problem in the tank so i tested my water and noticed that my phosphate and nitrate were high
Phos: 0.19 , Nitrate : 40 so i did two (40%) massive water change and right now my phosphate is 0 and nitrate is 10 ppm. i asked from two different fish store about the ideal level for nitrate and they gave two completly different answers.
One of them told me the nitrate needs to be close to zero and the other one said below 20 ppm is safe. So im kinda lost and i dont want to get the algea problem again. Does anyone know for sure ?
Thank you.

Them test kits stink get a good test kit phosphate are to high nitrate way to high I like chem per blue elite it will drop your po4 to much food might be your no3 problem