Phosphate 0.4ppm how high is too high?

[vdubers]

TLDR the general consensus around phosphate levels seems to be changing. How high is too high? Mine is currently 0.4ppm. Leave it as it is or lower it?

Hi all so a couple of months ago I requested your help around increasing nutrient levels. Well I picked up a sun coral on the 9th December and with the additional feedings my nutrients are increasing.

My tank is currently at 0.4ppm phosphate and 15ppm nitrate but things are looking good no algae issues or browning issues at the moment although I have only recently picked up some more acropora frags.

I guess my main question is if things are looking good should I leave it as is or should I lower it? My understanding is higher phosphate can inhibit calcification?

I have lowered phosphate using GFO in the past but my tank always seemed better without it. I stopped using GFO around October 2024.

Data, video and pictures included below.

Total input vs output

Input traditionally per day
1 3x6 inch sheet of nori
2 cubes bcuk mysis
live brine shrimp twice a day
1 frozen mussel
50ml live phytoplankton
5ml easy reef booster
5ml easy reef easy sps

Sun coral feeding additional input
4ml Red Sea ab+ amino acid
3ml liquid mysis
2ml liquid Calanus
1ml oyster feast


Output
Aquavitro 500 skimmer with dual pump recirculating set up
DIY algae turf scrubber 18x12inches lit for 16 hours a day. Changed once every two weeks.
Filter floss changed twice weekly
5.5 litres per day automatic water change

Recent nutrient levels

Nitrate

* 6 Dec 2024 at 09:02:14: 18.3 ppm
* 13 Dec 2024 at 10:18:58: 20.6 ppm
* 20 Dec 2024 at 09:05:44: 15.9 ppm
* 27 Dec 2024 at 09:32:49: 15.3 ppm
* 3 Jan 2025 at 09:33:17: 11.8 ppm
* 10 Jan 2025 at 09:47:41: 12.2 ppm
* 17 Jan 2025 at 09:24:39: 13.6 ppm
* 24 Jan 2025 at 09:33:39: 12.8 ppm
* 31 Jan 2025 at 09:01:21: 12.5 ppm
* 6 Feb 2025 at 09:14:59: 13.8 ppm
* 14 Feb 2025 at 09:19:36: 15 ppm

Phosphate

* 6 Dec 2024 at 09:03:57: 0.218 ppm
* 13 Dec 2024 at 10:20:25: 0.055 ppm
* 20 Dec 2024 at 09:07:14: 0 ppm
* 27 Dec 2024 at 09:34:26: 0.144 ppm
* 3 Jan 2025 at 09:34:51: 0.08 ppm
* 10 Jan 2025 at 09:49:23: 0.202 ppm
* 17 Jan 2025 at 09:27:11: 0.331 ppm
* 24 Jan 2025 at 09:35:51: 0.141 ppm
* 31 Jan 2025 at 09:04:05: 0.328 ppm
* 6 Feb 2025 at 09:16:52: 0.365 ppm
* 14 Feb 2025 at 09:21:25: 0.408 ppm

Latest parameters
Salinity 34.5
PH around 8.1-8.3
Alkalinity around 8.5-9dkh
Magnesium 1380 (working on increasing)
Calcium around 400 (working on increasing)

Thanks for reading

Scrubber growth after 2 weeks

 

[Randy Holmes-Farley]

Randy’s Thoughts on Nutrient Target Ranges

Thoughts on Nutrient Target Ranges by Randy Holmes-Farley Almost nothing in the world of reef aquarium chemistry causes as much discussion as selecting and maintaining ranges for nitrate and phosphate. Some aquarists want low targets, some want...

www.reef2reef.com

4. 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.

 

[vdubers]

Randy’s Thoughts on Nutrient Target Ranges

Thoughts on Nutrient Target Ranges by Randy Holmes-Farley Almost nothing in the world of reef aquarium chemistry causes as much discussion as selecting and maintaining ranges for nitrate and phosphate. Some aquarists want low targets, some want...

www.reef2reef.com

4. 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.

Thanks Randy the article was a really interesting read. Sorry I must have missed that when I was searching the past couple of days.

Do you draw the recommendation of the 0.3ppm phosphate being the upper limit because beyond this the risk for inhibiting the calcification rate increases?

I sadly can’t access the full paper in your article to check the levels they studied.

 

[Randy Holmes-Farley]

Thanks Randy the article was a really interesting read. Sorry I must have missed that when I was searching the past couple of days.

Do you draw the recommendation of the 0.3ppm phosphate being the upper limit because beyond this the risk for inhibiting the calcification rate increases?

I sadly can’t access the full paper in your article to check the levels they studied.

Not necessarily, no. I actually had the limit at 0.4 in my first draft. Corals may well calcify more slowly as phosphate rises, but they still can thrive at levels high than yours. Richard Ross's tank (pictured in the article) is an example of that.

 

[vdubers]

Not necessarily, no. I actually had the limit at 0.4 in my first draft. Corals may well calcify more slowly as phosphate rises, but they still can thrive at levels high than yours. Richard Ross's tank (pictured in the article) is an example of that.

Thanks again for your help Randy. Yeah I did see his tank. Definitely looks like it’s thriving. Certainly food for thought thank you

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing. :)

 

[KStatefan]

I use 0.4 phosphate as my trigger to reduce it. currently using phosphate Rx 20 drops in my 1100 gallons when above 0.4 ppm. That should reduce it 0.17 ppm.

 

[LibertyAquatics513]

I been combating high nutrients on my reef also. I been running a small amount of GFO in my reactor. My phos was as high as 1.23 before. Now sitting at around 0.4 also.

 

[vdubers]

I use 0.4 phosphate as my trigger to reduce it. currently using phosphate Rx 20 drops in my 1100 gallons when above 0.4 ppm. That should reduce it 0.17 ppm.

Any negative effects? I’ve always been weary of trying lanthanum chloride I like the precise nature you seem to be able to get with it vs GFO but I only run filter floss rather than filter socks. And having a couple of tangs I would hate to use it to try and improve the tank even though things look good just to end up killing or harming my fish.

 

[KStatefan]

Any negative effects? I’ve always been weary of trying lanthanum chloride I like the precise nature you seem to be able to get with it vs GFO but I only run filter floss rather than filter socks. And having a couple of tangs I would hate to use it to try and improve the tank even though things look good just to end up killing or harming my fish.

I have not seen any. I have one yellow tang. I am dosing slowly 5 drops into 5 micron sock then wait 5 minutes for the next 5 drops. I am also not doing this with the display return. I am using a pump to pull from my refugium then into the sock that in in the refugium just for this.

 

[vdubers]

I have not seen any. I have one yellow tang. I am dosing slowly 5 drops into 5 micron sock then wait 5 minutes for the next 5 drops. I am also not doing this with the display return. I am using a pump to pull from my refugium then into the sock that in in the refugium just for this.

Ah that’s an idea I didn’t think of that. I could probably set something up similar thanks will keep that in mind.