Trying not to chase numbers but... Nitrate weirdness!

[ParticleMan]

Hello All, my tank is just over 3 months old and I'd like to think is doing fairly well. I was having phosphate issues for awhile but seem to be over that for the most part. I'm starting to hit the ugly phase with a pretty aggressive green film algae problem and some light diatoms on the sand. Now my biggest problem is my Nitrate is bottoming out. Below is my tank information and current stock. For the past month or so it's been running just under 10ppm but ever since my 8 gallon water change on 10/5 my Nitrates have been dropping. On 10/8 it was down to 2, and today I tested and they are 0. All the while my Phosphate has gone from .11 to .07 which seems good. I am actually have less chaeto now in the refugium than before the water change so I am stumped. I feed about 1 cube worth in total of frozen Mysis, Emerald Entree, and Spiralina Brine Shrimp a day. I got some Britewell NeoNitro to start dosing but can't understand how a new tank could be having that sort of Nitrate problem. Could it be too efficient? Can someone offer me some clues as to what to do. I was going to start adding some corals and my last fish (Blue Flasher Wrasse) but not sure what to do at this point.

System Overview
Tank: JBJ 45-RF (45 gallons)
Cycle Start: July 13 2025 (FritzZyme 9 + Dr. Tim’s Ammonium Chloride)
Lighting: AI Hydra 32 HD — BRS AB+ schedule
Flow: Hygger HG-951 + Platinum Slim Wave 1600
Temperature Control: Heater (Chamber 5) + Tunze ATO System

Filtration / Rear Chambers
Chamber 1 – inTank basket (Filter fiber + sponge / Purigen + Carbon / PhosGuard)
Chambers 2 + Return – Seachem Matrix + Bio Rings
Chamber 5 – Heater + Tunze ATO sensor
Chamber 6 – InTank basket Refugium with Chaeto + Rock Rubble + ChaetoMax light (reverse 12 hour cycle), seeded with EcoPods.

LiveStock
Pair of Extreme Mocha Vinci Clownfish
Yellow Watchman Goby + Tiger Pistol Shrimp
Purple Firefish
Orange Back Fairy Wrasse
4 Blue Leg Hermits, 2 Scarlet Hermits, 2 Nassarius, 3 Trocus, 2 Peppermint Shrimp. 1 Tuxedo Urchin.
1 Frammer (4 Heads)

2 Months of Water Parameters
Date Alk Ca Mg NO₃ PO₄ pH
8 / 25 8.1 370 1250 5 0.08 8.1
9 / 04 7.2 448 1070 9.8 0.25 8.2
9 / 09 7.4 380 1250 7 0.14 8.1
9 / 16 6.9 561 1280 7.6 0.18 8.0
9 / 20 7.6 401 1210 7.8 0.23 —
9 / 23 7.8 465 1155 6.7 0.12 8.0
9 / 25 7.5 — 1430 — 0.13 —
9 / 27 7.3 407 1300 — — —
9 / 28 7.2 412 1260 6.4 0.09 —
10 / 01 8.2 389 1178 5.7 0.14 8.1
10 / 09 7.6 437 1285 2 0.11 —
10 / 11 7.8 405 1510 0 0.07 8.0

 

[Pod_01]

So couple of things, water change will reduce NO3 but it will not reduce PO4. So part of your drop in NO3 is caused by water change.

Growing algae (ugly stage) will consume NO3 and some PO4. Both are required building block for algae and corals.

Since you don’t have corals algae is using up the NO3 and PO4.

As an aside for corals to thrive you do require PO4 and for a new tank my suggestion would be to have a reading of 0.1-0.25ppm.
In my opinion having PO4 values below 0.1ppm is for seasoned reefers.

NO3 can be at 1ppm but 1-5ppm provides safety margin to ensure corals have enough. Amino acids are good source of N for corals or another preferred source of N for corals is ammonia dosing.

Good luck,

 

[Dan_P]

Hello All, my tank is just over 3 months old and I'd like to think is doing fairly well. I was having phosphate issues for awhile but seem to be over that for the most part. I'm starting to hit the ugly phase with a pretty aggressive green film algae problem and some light diatoms on the sand. Now my biggest problem is my Nitrate is bottoming out. Below is my tank information and current stock. For the past month or so it's been running just under 10ppm but ever since my 8 gallon water change on 10/5 my Nitrates have been dropping. On 10/8 it was down to 2, and today I tested and they are 0. All the while my Phosphate has gone from .11 to .07 which seems good. I am actually have less chaeto now in the refugium than before the water change so I am stumped. I feed about 1 cube worth in total of frozen Mysis, Emerald Entree, and Spiralina Brine Shrimp a day. I got some Britewell NeoNitro to start dosing but can't understand how a new tank could be having that sort of Nitrate problem. Could it be too efficient? Can someone offer me some clues as to what to do. I was going to start adding some corals and my last fish (Blue Flasher Wrasse) but not sure what to do at this point.

System Overview
Tank: JBJ 45-RF (45 gallons)
Cycle Start: July 13 2025 (FritzZyme 9 + Dr. Tim’s Ammonium Chloride)
Lighting: AI Hydra 32 HD — BRS AB+ schedule
Flow: Hygger HG-951 + Platinum Slim Wave 1600
Temperature Control: Heater (Chamber 5) + Tunze ATO System

Filtration / Rear Chambers
Chamber 1 – inTank basket (Filter fiber + sponge / Purigen + Carbon / PhosGuard)
Chambers 2 + Return – Seachem Matrix + Bio Rings
Chamber 5 – Heater + Tunze ATO sensor
Chamber 6 – InTank basket Refugium with Chaeto + Rock Rubble + ChaetoMax light (reverse 12 hour cycle), seeded with EcoPods.

LiveStock
Pair of Extreme Mocha Vinci Clownfish
Yellow Watchman Goby + Tiger Pistol Shrimp
Purple Firefish
Orange Back Fairy Wrasse
4 Blue Leg Hermits, 2 Scarlet Hermits, 2 Nassarius, 3 Trocus, 2 Peppermint Shrimp. 1 Tuxedo Urchin.
1 Frammer (4 Heads)

2 Months of Water Parameters
Date Alk Ca Mg NO₃ PO₄ pH
8 / 25 8.1 370 1250 5 0.08 8.1
9 / 04 7.2 448 1070 9.8 0.25 8.2
9 / 09 7.4 380 1250 7 0.14 8.1
9 / 16 6.9 561 1280 7.6 0.18 8.0
9 / 20 7.6 401 1210 7.8 0.23 —
9 / 23 7.8 465 1155 6.7 0.12 8.0
9 / 25 7.5 — 1430 — 0.13 —
9 / 27 7.3 407 1300 — — —
9 / 28 7.2 412 1260 6.4 0.09 —
10 / 01 8.2 389 1178 5.7 0.14 8.1
10 / 09 7.6 437 1285 2 0.11 —
10 / 11 7.8 405 1510 0 0.07 8.0

Bacteria and algae are consuming the ammonia before it can be converted to nitrate. No mystery, just everyone seems to forget that a brightly lit body of water grows algae. Just start adding nitrate. Sodium nitrate is cheaper but you will have to measure a solid, dissolve it in RODI before dosing. Nit a biggy unless math frightens you.

 

[CHSUB]

can't understand how a new tank could be having that sort of Nitrate problem

The problem is there is no problem, only the one you’re inventing. Decades of tanks and hobbyists have maintained tank with hobby test kits showing 0 no3. Personally my reading go back to mid nineties when I stop using trickle filters and no3 when to zero on hobby test kits. Don’t get confused by the noise.

 

[emvanburen]

Different phase of tank will consume NO3 and PO4 differently. I had to dose nitrate (Neonitro, then ammonium bicarbonate ) for a while. Where your tank will land long term is dependent on stocking, feeding, husbandry and system. Just keep testing and think big picture - what raises, what lowers, and try and avoid fighting w yourself where you are doing something to add and something else to subtract Lt at same time . I shoot for .1 PO4 and 10 NO3 to keep coral happy and weird algae at bay but people have success w many different numbers. Zero, however, is not typically one of them.

 

[skey44]

Zero nitrate has been an issue for me since day one. I was reluctant to add nitrates and thought I could just feed and add a lot of fish. Then got Dinos. Now I have a lot of fish and a lot of corals and still can bottom out nitrates if I don’t add neonitro daily. And believe me I feed heavy. Probably equivalent of 3-4 cubes daily plus pellets and nori flakes. For a tank your size a bottle of neonitro will likely go a long way. Just dose it, keep the nitrates above zero to avoid imbalances that cause Dinos.

Modern tanks can bottom out phosphate and nitrate issues. A lot of documentation and discussion regarding reasons. I keep it simple and just dose the nitrates.

What test kit are you using? And you only have one zero reading listed there, could have been test error.

But yes it sounds like your in tank algae and chaeto are binding/using all the available nitrogen in your tank.

 

[Randy Holmes-Farley Verified Community Expert]

Here’s my recommendation:

https://www.reef2reef.com/ams/randy’s-thoughts-on-nutrient-target-ranges.1087/
From it:
. What targets seem reasonable? Of course, that depends on all the other factors at play, such as types of corals, availability of ammonia, particulate foods, etc. However, for a mature mixed reef, this would be how I personally would run it:

• Let nitrate float between 5 ppm and 50 ppm. I’d use gentle export in this range, such as growing macroalgae.
• Above 50 ppm, I’d begin to focus more on reducing it, by organic carbon dosing, turf or macroalgae, etc.
• Below 5 ppm, I’d begin to dose ammonia or feed more. The target level might drop lower if dosing ammonia, just like the heavy in/heavy out scenario where nitrate may not be as needed.
• Let phosphate float between about 0.06 ppm and 0.3 ppm. This range is higher than I’ve recommended in the past. I’d use gentle export in this range, such as growing macroalgae.
• Above about 0.3 ppm, I’d begin to focus more on reducing it, by turf or macroalgae, or a binder such as GFO or lanthanum (has its own risks to tangs). If a binder: GO SLOW. Turf and macroalgae will typically be slow enough.
• Below 0.06 ppm, I’d begin to dose sodium phosphate or feed more to get the level up.

 

[ParticleMan]

This is all great advice and thank. From a lot of what I've read this sounds fairly normal for a tank my age. After my 8 gallon w/c on Sunday I tested Monday and nitrate went up to .04 and phos went to .09. I went ahead and dosed 5ml of neonitro expecting a 1 to 2 ppm bump. Of course when I tested it Tuesday evening I was back to 0 nitrates and down to .02 phosphates. Seems my chaeto and/or bacterial colonies are just hungry for nitrates and phosphates. I pulled the phosguard out and dosed another capsule of neonitrate. Hoping for better results when I test tonight.

 

[sixty_reefer]

It’s worth mentioning that you are most likely dealing with a phytoplankton bloom of dinoflagellates.

 

[ParticleMan]

Oh that dosent sound great. I thought dinos where brown and nearly impossible to get rid of. It only seems to be on the glass and walls. The sand just have the usual dusty diatoms. What should I do at this point?