ICP results shows elevated phosphate, while test show zero, and other advice

[Blennioidei]

Hi,

Display Tank: https://modernreef.eu/visitor-user-lab-report/?data-id=30643&access-token=Q0U065Zqbt
RODI: https://modernreef.eu/visitor-user-lab-report/?data-id=30680&access-token=KXouRCbYeF

I just recived my first ICP result, for my 6 months old mixed reef. I have some questions, maybe some of you can help.

1. I have been struggling to raise my phosphate levels since the beginning of my tank, and my nitrate levels have been in the 50-75 range. The phosphate levels were tested with Hanna LR a few months earlier, which showed 0.01, and I was testing with both Salifert and Aquaforest tests, which showed either zero or the slightest amount of phosphate. I was dosing phosphate to the tank daily, but I only dosed after I took the water sample that day. With the dosing, my nitrate levels actually started to come down. The test shows 0.68 mg/l PO4. What could have caused this? The sample was in transit for 10 days—maybe that? I just did a test, and it shows around ~0.01, I will get an additional test, but I highly doubt my levels are that high.
2. Vanadium, cobalt, chromium, iron, manganese, and nickel are low or undetectable. How should I handle this? Buy them individually, or is there a better way?
3. Zinc and antimony are high. I guess I have to search for something malfunctioning or rusting. Is there any other value that would indicate this?


Tank is looking okay-ish. When I don't dose phosphate, I have little alge growth, slow coral growth. When I dose, I have better coral growth(i mainly monitor on my zoas), but also some cyano on the sand, and alge(on back wall).


Thanks for the advice

 

[Gumbies R Us]

@Randy Holmes-Farley

 

[Randy Holmes-Farley Verified Community Expert]

1. I have been struggling to raise my phosphate levels since the beginning of my tank, and my nitrate levels have been in the 50-75 range. The phosphate levels were tested with Hanna LR a few months earlier, which showed 0.01, and I was testing with both Salifert and Aquaforest tests, which showed either zero or the slightest amount of phosphate.

Have you not restated phosphate since the test months ago? Things can change over months, especially in a new tank.

 

[Subsea]

Hi,

Display Tank: https://modernreef.eu/visitor-user-lab-report/?data-id=30643&access-token=Q0U065Zqbt
RODI: https://modernreef.eu/visitor-user-lab-report/?data-id=30680&access-token=KXouRCbYeF

I just recived my first ICP result, for my 6 months old mixed reef. I have some questions, maybe some of you can help.

1. I have been struggling to raise my phosphate levels since the beginning of my tank, and my nitrate levels have been in the 50-75 range. The phosphate levels were tested with Hanna LR a few months earlier, which showed 0.01, and I was testing with both Salifert and Aquaforest tests, which showed either zero or the slightest amount of phosphate. I was dosing phosphate to the tank daily, but I only dosed after I took the water sample that day. With the dosing, my nitrate levels actually started to come down. The test shows 0.68 mg/l PO4. What could have caused this? The sample was in transit for 10 days—maybe that? I just did a test, and it shows around ~0.01, I will get an additional test, but I highly doubt my levels are that high.
2. Vanadium, cobalt, chromium, iron, manganese, and nickel are low or undetectable. How should I handle this? Buy them individually, or is there a better way?
3. Zinc and antimony are high. I guess I have to search for something malfunctioning or rusting. Is there any other value that would indicate this?


Tank is looking okay-ish. When I don't dose phosphate, I have little alge growth, slow coral growth. When I dose, I have better coral growth(i mainly monitor on my zoas), but also some cyano on the sand, and alge(on back wall).


Thanks for the advice

I have read your other tank threads and will comment with some observations:

Dosing a phosphate limited tank with phosphate should promote algae uptake of all nutrients. So expect nitrates to be consumed when phosphate is available for photosynthesis. Normal macro algae ratio of N:P is 30:1. With respect to trace minerals required for macro algae growth, iron by far is a major supplement.

On fishless grow out systems, I dose liquid kelp concentrate every other day and ammonia every day.

This 55G seaweed growout tank gets 10 ml of ammonia twice a day during photosynthesis.

 

[Blennioidei]

Hi guys, thanks for the replies! Here’s what I’ve been up to since my last post:

I got a Hanna ULR Phosphate tester to get better readings. While dosing 5 ml of Modern Reef Phosphate+ (here’s the link: Modern Reef Phosphate+), my phosphate readings has been between 0.01-0.05 ppm(its a small sample size, planning to track it closer after I set up the doser).

Here’s what I’m currently dosing:

- 5 ml Modern Reef Phosphate+ after lights out (testing a doser, so this will be automated soon).
- 10 ml Aquaforest NitraPhos Minus around midday (also going on the doser soon).
- 3-3 drops of Aquaforest -NP Pro and Pro Bio S, dosed alongside the phosphate at night.
I’ve been trying to feed a little less, but I don’t think that’s the main issue. There’s some algae growth, but nothing crazy. I still think the system is phosphate-bound. My ICP test also showed undetectable iron, which could be part of the problem. I’ve ordered Fe, I, and Mn supplements and plan to start dosing those(will look into liquid kelp Subsea, thanks for the tip).

Another thing I realized is that I might have been cleaning my sand too often during my weekly 10% water changes. I’ve been reading about anaerobic zones and decided to leave the sandbed alone for now. I’m switching to bi-weekly, larger water changes to see if that helps.

Here’s my plan going forward:

1. Set up my doser to consistently dose Phosphate+ and NitraPhos Minus.
2. Start dosing Fe, I, and Mn.
3. Gradually increase the phosphate dose based on Hanna ULR readings until I see consistent levels around 0.04–0.06 ppm (maybe higher? since I don’t have SPS).
4. Leave the sandbed alone for a while.
5. Switch to bi-weekly 20% water changes to help stabilize the tank and make trends easier to track.

I’ve already started doing most of this, and my latest nitrate test (Salifert) showed around 50 ppm but with a
much lighter color than usual. Hoping to hit 25 ppm soon.

About the heavy metal issues :
I noticed some rust in my refugium light, so I’ve removed that and hope it addresses the zinc and other heavy metal levels. I’ve also ordered new RODI filters and a heavy metal remover supplement. Fingers crossed this sorts it out!

Let me know what you guys think or if there’s anything I might be missing.