Help Balancing DIY Dosing: Adding Phosphate to Ammonium Bicarbonate Stock?

[madlos123]

Hey everyone,

I’m currently running a 90-gallon established reef and have hit a wall with nutrients—both Nitrates and Phosphates are bottomed out at zero either from algae or coral consumption.


I have a tank full of corals of SPS and LPS and only have 3 fish. 3 inch Tomini Tang, 2x 2 inch Royal Gramma. Due to financial and time constants I cant add more fish currently. I have noticed especially my LPS they are paler than usual. SPS are growing but would like better coloration/growth.


To combat this, I’ve started dosing an Ammonium Bicarbonate stock solution (20 mg per 1 L of RODI) this week. I’m currently dosing 7.7 ml per day via a 1.1 ML BRS 2 Part doser.


I have read in a thread by Miami Reef that you can add phosphate in the same stock solution. I want to avoid a nutrient imbalance and would like to add Phosphate directly to this same stock solution. I just wanted to get some phosphate for the corals or ideally the optimal level.


What kind of phosphate I can mix?

How many mg per liter can I add.


I might have Monopotassium Phosphate on hand.

Does anyone have experience mixing these two in a single stock solution?


Thank you

 

[Randy Holmes-Farley Verified Community Expert]

While there are some situations where combining them can be convenient, I would not start off that way since it is not possible to know how much phosphate you will need to bring the levels up to an appropriate level (due to rock and sand binding).

My recommendation is to add 0.03-0.05 ppm phosphate once a day for several days, then measure and see where the phosphate stands.

Monopotassium phosphate is OK if you have it, but long term I think the sodium versions are better to keep potassium from rising. Short term that will not be an issue.

 

[Randy Holmes-Farley Verified Community Expert]

Your ammonia dosing solution is EXTREMELY weak, if you really mean 20 mg/L. My recipe is 20 g/L, and adding 7.7 mL per day (of my recipe) as you are would only add 0.1 ppm of NH3.

https://www.reef2reef.com/threads/diy-ammonia-dosing-for-low-nitrate-systems.987087/

 

[rishma]

I have dosed ammonia bicarbonate and sodium phosphate dibasic for a long time. I have often thought it would be good to combine the two and save a dosing head.

However, my experience has been, even with extremely precise feeding in a well established tank, my nitrogen and phosphorus consumption in the tank is not static. I occasionally need a small adjustment of each of them. I probably adjust monthly. Because if this I concluded that mixing them is not helpful since I have enough dosing heads to dose them separately.

 

[madlos123]

Your ammonia dosing solution is EXTREMELY weak, if you really mean 20 mg/L. My recipe is 20 g/L, and adding 7.7 mL per day (of my recipe) as you are would only add 0.1 ppm of NH3.

https://www.reef2reef.com/threads/diy-ammonia-dosing-for-low-nitrate-systems.987087/

Yeah sorry its 20 g/liter. Just started dosing.

 

[Randy Holmes-Farley Verified Community Expert]

OK, that's good. :)

 

[madlos123]

I was researching the old fasion way. I found a thread called "The Complete Guide to Raising Nutrients" by Miami Reef and I was calculating it all by myself on the phosphate section. I got confused and lost. So I tried copying and pasting it in google ai, which is just spat the most vague answers even asked to be more specific with numbers.

So this is my first time using ChatGPT, just copied and pasted the phosphate tread and i put in

"do calculations for 90 gallon with 40 gallon sump with rock and sand displacement and not fully filled sump"

and this spat out for me below.

Just making sure so im not going off the cliff just blindly following my GPS on the early days lol.

Im guessing it's its Loudwolf Sodium Phosphate Dibastic 4 ounze Bottle 98%+ food grade fine powder that most people buy? from amazon.

Stock solution:

Dissolve 3 g of Sodium phosphate dibasic in 1 Liter of freshwater.
__________________________________________________

Now, let’s adjust the total system volume:

1. Display Tank (90 gallons) with rock/sand displacement:
   • 15% displacement of 90 gallons = 13.5 gallons displaced.
   • Remaining volume in the display tank = 90 gallons - 13.5 gallons = 76.5 gallons.
2. Sump (assumed 30 gallons):
   76.5gallons (display)+30gallons (sump)=106.5gallons.
   This is the new adjusted total system volume.
   • So now, the system volume is:

Convert to Liters:

• 106.5 gallons × 3.78541 = 403.4 liters.

Sodium Phosphate Dibasic Dosing for 403.4 Liters:

Using the original recipe for 1 mL per 100 L to raise phosphate by 0.02 ppm, let’s calculate:

1. Dose for 100 L (to raise by 0.02 ppm): 1 mL.
2. For 403.4 L:
   100L 1mL × 403.4L = 4.034mL.
   So, 4.03 mL will raise phosphate by 0.02 ppm in your system.

To Raise PO₄ by 0.15 ppm (Initial Dose):

For a 0.15 ppm increase, you’d need to dose:

0.02ppm 0.15ppm × 4.03mL = 30.23mL.

So, for an initial strong dose of 0.15 ppm, you should dose approximately 30.2 mL of Sodium phosphate dibasic (Na₂HPO₄) for your system.

---

Summary for Your System (Adjusted Volume of 106.5 Gallons):

• To raise phosphate by 0.02 ppm: Daily Dose of 4.03 mL of Sodium phosphate dibasic (Na₂HPO₄).
• To raise phosphate by 0.15 ppm (initial strong dose): Dose 30.2 mL of Sodium phosphate dibasic (Na₂HPO₄).

 

[madlos123]

Lol i broke chatgpt asking how to mix it with the anmonium bicarbonate. Good thing i have another 1.1ml BRS 2 part doser to dose it separately. Oh well time to go back to the drawing board.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t like to spend time correcting ai stuff.

Just use this calculator. It will be close enough:

theplantedtank.co.uk/calculator.htm

 

[madlos123]

I just finished reading 40 ish of the 80 page thread about ammonia dosing and realized i placed my dosing tube at the same location where my kalkwasser stirrir dumps. Its on the highest flow where water first enter the sump from the pipes to the filter sock area. My kalkwaser stirrir is connected to my ato so its not on a set timer. Although the kalk tube direction is to the left and the ammonia dosing tube is to the right. Its probably not going to do anything since its only dosed for 7 min per day for the ammonia. But hey theres a chance lol.

Question:

I wonder if its better if I dose it on the filter sock area where its high flow but I have a lot of rock on the 2nd chamber and protein skimmer and possible reaction from the kalk.

Vs

Dosing it on the bubble trap/ baffle before the return pump and after the protein skimmer so it goes straight to the display.

I just dont want to ruin my return pump.
------------------------------------------------------------------
I only get to see my reef tank once a week so well see what happens when i get to see it.
And adjust the dosing tube location.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t think it matters where you dose ammonium bicarbonate solution as long as it is not right onto organisms.

 

[madlos123]

Alrighty, im at 36 ml per day for ammonium bicarbonate. 9 ml per dose every 2 hours.
Increase of 9 ml per week.

Added the 30.3 ml of sodium phosphate dibasic initially then.
Started dosing sodium phosphate dibasic at 4 ml per day.

Corals are growing crazy fast. Like new and faster growths i have never seen before especially on my fox flame acropora, hawkins, garf bonsai, pocillopora grandis, and everything.

I have not tested anything yet, just looking at the reactions from the corals for now.

In the past i have dosed nitrate and phosphate and that always seem to make the corals and the whole tank angry after 3 weeks. So dosing ammonia seem to be in good track.

Still having red cyano.

I noticed some white crusty stuff on the surface on the water in the sump baffle before the return. Im guessing thats from kalkwasser and ammonium bicarbonate reaction?

So:
I have moved my dosing tubes (ammonium and phosphate only) near the return pump chamber on the left.

Question.
Does sodium phosphate dibasic cause precipitation on pumps like kalkwasser does?

Im assuming nothing since its dosing clear.

I know i read it should not be mixed with kalkwasser as it will precipitate.

 

[Randy Holmes-Farley Verified Community Expert]

I don't think there should be precipitation issues dosing that form of phosphate.

 

[madlos123]

I only get to see my tank once a week.

So i just checked today. My jason fox fox flame is somewhat angry. My hawkins is also kinda angry.

Everything is happy even my garf bonsai and purple valida is happy. So im not sure what happened with fox flame and hawkins.

I did notice that the yellow porites is shedding its skin/angry. So not sure if its toxins in the water. I do have palythoa grandis. So not sure.

Or i already had saturated phosphate in the rocks and sand and it got too high when i added the 30.2 ml? Plus daily dosing.
Maybe?

It only got angry after the 4th batch of ammonia (4x 9 ml) and 1st dosing of phosphate 30.2 ml and 1 week of phosphate 4 ml per day.

So i backed down the ammonia to 3x 9 ml and stopped phosphate.

Added 1 cup carbon in the sump sock area.

Well see next week.

 

[Randy Holmes-Farley Verified Community Expert]

Sorry to hear some things are not liking it.

Phosphate on rock doesn’t saturate in the sense you are referring. The higher the concentration of phosphate in the water, the more will bind.

 

[madlos123]

Ah thanks good to know

I just tested.

8.6 dkh ( brand new salifert)

36 SG ppt

8.67 pH (ph monitor, i have to double check this with api) probably bec i added new kalkwasser in my avast stirrer causing the new overflow high ph
Or the probe went bad due to contamination ( i have thread about it)

5-10 ppm nitrate (api nitrate)

0.93 phosphate (hannah UL reagent expired 2022) So not sure ill double check.
The vial turned blue right away, i knew it was high lol.
Probably from either testing error due to expired reagent or dosing error from stock tank too much or my digital plug in timer stuck on (which happened when i dosed 2 part with calcium)
Or was dosed too much or the tank didnt need it.
No algea outbreak which is surprising.
Still have cynano.

So either do a water change
Last time i had high phosphates, i used gfo and that made the corals angrier lol so i wont be doing that until i confirm things.

My tank seem to bounce back if i leave it alone.
But it's only 3 corals soo
Well see

 

[madlos123]

Weird thing is i dont see no darkening of corals like what i heard from other people due to high phosphates.
This looks more like a burn or some kind of expelling zooxanthellae

 

[Randy Holmes-Farley Verified Community Expert]

High phosphate does not necessarily cause coral problems or darkening, but I’d certainly stop dosing it if the test is accurate.

 

[madlos123]

Got an update

Phosphate is now 0.54
Ph is 8.2

LPS corals are happy. The only ones that got hit is the fox flame and the hawkins acropora.

My fox flame always looks like a brown coral anyway since the begginng so was planning to get that replaced a differnet reddish coral under 10,000k.

Hawkins maybe bummee about it since its the only bluish coral in my tank but not a big deal. . But hopefully ill get an oregon tort someday to get that replaced in that spot.

Cyano is worse, probably uptating the extra nutrients.

Everything else is happy.

Just cleaning my tank so its a little cloudy from the algae

 

[madlos123]

My ricordia mushroom yuma is up with the sps where its like 250+ par.
Also im really good at growing aiptasia
My purple valida and garf bonsai are really deep purple
My pocillopora grandis is loooking great.
Can you believe only 3 fish are sustaining or barely sustaining the nutrients in this system lol.