DIY Phosphate Dosing Recipe

[billyocean]

Thats the same I use to dose p04. Works

 

[Mschmidt]

So before I saw this thread, or even bothered to look for a recipe, I mixed 25g, maybe it was 35g with ro to make 250ml. There is quite a bit of precipitate so I assume it's fully saturated.

Do you happen to know or can figure the concentration of the solution?
I used this stuff if the kind matters much
Sodium Phosphate, Dibasic (Disodium), 99% min., 500 Grams https://a.co/d/9x6KN4m

 

[Miami Reef]

I’ll take a bite.

According to Wikipedia, sodium phosphate dibasic (disodium) has a max solubility of:

Disodium phosphate - Wikipedia

en.m.wikipedia.org

7.7 g / 100 ml at 20 °C

That means each clear portion of your solution should contain about 0.077 g per mL


To follow the recipe in this first post:

3 / 0.077 =38.961 or 39 mL of your solution in a L of water.

Dose 1 mL per 100 L to raise PO₄ by 0.02 ppm.

 

[Mschmidt]

Thanks man! That would make my solution 13 times stronger than your recipe?

That would mean 1 ml would raise 100L by .26ppm?

Edit, I'm a dumb. If fully saturated is 7.7 g. and your recipe is 3 g than it would be 7.7/3 times as strong.

 

[Miami Reef]

Your stock is 7.7 g/ 100 mL =0.077 g/mL or 77mg / mL
Mine is 3 g/1000mL=0.003 g/mL or 3mg/mL

77/3=25.667

Your solution is about 25.6x stronger or 2,467% stronger.

1 mL of yours will contain 77 mg sodium phosphate dibasic. Since there’s 66.9% phosphate by weight, 1mL would really contain 51.5 mg of PO4.


51.5mg/100L=0.515 mg/L or 0.52 ppm

Adding 1 mL per 100L will raise PO4 by 0.52 ppm when using your saturated solution.

 

[Miami Reef]

If fully saturated is 7.7 g. and your recipe is 3 g than it would be 7.7/3 times as strong.

Yours is 7.7 g per 100 mL
Mine is 3 g per 1000 mL

Divide total g by total mL to find out how much g/mL

7.7g/100mL=0.077 g/mL
3g/1000mL=0.003 g/mL

0.077/0.003=25.667x stronger or 2,466.7% stronger.

 

[Mschmidt]

Your stock is 7.7 g/ 100 mL =0.077 g/mL or 77mg / mL
Mine is 3 g/1000mL=0.003 g/mL or 3mg/mL

77/3=25.667

Your solution is about 25.6x stronger or 2,467% stronger.

1 mL of yours will contain 77 mg sodium phosphate dibasic. Since there’s 66.9% phosphate by weight, 1mL would really contain 51.5 mg of PO4.


51.5mg/100L=0.515 mg/L or 0.52 ppm

Adding 1 mL per 100L will raise PO4 by 0.52 ppm when using your saturated solution.

I forgot to look at the volume of water. I'm still a dumb. Thanks.

 

[Miami Reef]

I forgot to look at the volume of water. I'm still a dumb. Thanks.

You are not dumb. It’s a common mistake. Even the best chemists make errors.

 

[TwelveL16]

I could use some help. I’m just a dumb cop and this is a lot of math for me. I’m battling 0 phosphate with Dino’s. I’ve been adding 15 ML of brightwell neophos per the directions. Phosphates still showing 0 every morning I check it with Hanna phosphorus ULR 1736. How much of this neophos would add to get your recommend .10 - .15. Tank is 150gallons.

 

[Randy Holmes-Farley]

If you add 0.1 ppm, you won’t detect that much because some is consumed and siem
Binds to rock and sand. So you may need to do that several days in a row.

I literally do not even see directions or a potency on their current web site.

What does the bottle say for directions?

 

[Miami Reef]

I could use some help. I’m just a dumb cop and this is a lot of math for me. I’m battling 0 phosphate with Dino’s. I’ve been adding 15 ML of brightwell neophos per the directions. Phosphates still showing 0 every morning I check it with Hanna phosphorus ULR 1736. How much of this neophos would add to get your recommend .10 - .15. Tank is 150gallons.

Can you please share the dosing calculations on the bottle? How many mL raises how much PO4 in how many gallons or liters?

Or if there’s a phosphate concentration listed somewhere, that could also work.

 

[Miami Reef]

I literally do not even see directions or a potency on their current web site.

Same. I found this forum post from 2017, but I don’t know if the concentration is still the same today.

1 ml NEOPHOS will increase the phosphate concentration in 1 US-gallon (~3.8 L) by ~1.2 ppm; 1 drop from plastic bulb pipette (enclosed within bottle) will increase the concentration in the same volume of water by ~0.06 ppm.

 

[TwelveL16]

I could use some help. I’m just a dumb cop and this is a lot of math for me. I’m battling 0 phosphate with Dino’s. I’ve been adding 15 ML of brightwell neophos per the directions. Phosphates still showing 0 every morning I check it with Hanna phosphorus ULR 1736. How much of this neophos would add to get your recommend .10 - .15. Tank is 150gallons.

Can you please share the dosing calculations on the bottle? How many mL raises how much PO4 in how many gallons or liters?

Or if there’s a phosphate concentration listed somewhere, that could also work.

It says multiply tank capacity in gallons x ppm desired x 3.785.

So if I’m doing it correctly 150x .15x 3.785 = 85.163 ML??

 

[TwelveL16]

 

[Miami Reef]

Math is correct. Its essentially converting your tank capacity from gallons to liters, then it multiplying it by how much increase (in ppm) desired.

 

[TwelveL16]

Math is correct. Its essentially converting your tank capacity from gallons to liters, then it multiplying it by how much increase (in ppm) desired.

And this is what you would do? For some background, I’ve raised the sensor on my fleece roller, turned off my skimmer, removed my chaeto, overfed frozen mysis and dosed phos for the past 4 days and still reading 0.

 

[TwelveL16]

Math is correct. Its essentially converting your tank capacity from gallons to liters, then it multiplying it by how much increase (in ppm) desired.

Pics of my tank as it stands right now.

Pics of my tank as it stands the Dino’s get worse as the day progresses.

 

[Miami Reef]

I outlined in an article of mine exactly how I would approach filtration for low nutrient tanks:

The Complete Guide to Raising Nutrients

Raising nutrients isn’t always easy; for some systems, it can feel like an uphill battle: confusing, frustrating, and full of contradictory advice. It’s not always clear which products to use, what to dose, or which filtration methods to adjust or remove. Chronically low nutrients are...

www.reef2reef.com

Here’s a breakdown of what’s safe to adjust, and what’s better left in place:

Protein Skimmers
Skimmers should generally remain running. They are not effective at removing nitrate or phosphate directly, and they serve important functions such as removing organics, bacteria, heavy metals, and CO₂, while also supporting oxygen saturation. Removing the skimmer is rarely beneficial and may cause more harm than good.

Bacterial Export (Carbon Dosing, Biopellets, Denitrators)
Bacterial-based filtration methods are highly effective at reducing nutrients, particularly nitrate. If your tank is already running low, it’s often best to reduce or pause these approaches until levels increase. Some modern products, like NP Bacto Balance, include some nutrients in their formulation to help prevent nutrient depletion: a promising compromise in certain systems. Nevertheless, scaling back the dosage is a safe and flexible option when nutrients are trending too low.

Refugiums
Algae-based filtration can be scaled back if desired, but completely removing them is usually not required. A shortened photoperiod is a gentler alternative to reduce export while preserving the pH and oxygen benefits refugiums offer, not to mention the habitat they provide for zooplankton.

Water Changes
You can reduce their frequency or volume, but there’s no need to avoid them completely. Water changes offer benefits beyond nutrient control, and no other method removes organics as effectively. They don’t just dilute: they realign. If an element is too low, the new water brings it up. If it’s too high, the water change brings it down. Over time, this pulls parameters toward the baseline of your salt mix.

Mechanical Filtration (Filter Socks, Floss, Roller Mats)
These have minimal effect on dissolved nutrients and don’t need to be removed. You can keep them for water clarity and detritus control.

Chemical Media (Activated Carbon, Purigen)
These do not significantly affect nitrate or phosphate levels and can remain in the system. Their benefits lie more in water clarity and the removal of organic discoloration or toxins.

Phosphate Removers (GFO, PhosGuard, etc.)
If phosphate is already undetectable or bottomed out, remove these immediately. Continuing to run phosphate adsorbers can starve corals and increase the risk of dinoflagellate outbreaks.

Other Media (Matrix, Bio Bricks, Zeolites)
These have little to no direct impact on nutrient levels and can be left in place without issue.





I would stock up on sodium phosphate. The one linked in the first post is significantly more inexpensive than Brightwell’s and actually has a food grade rating, which is as pure as it gets.


You can easily outcompete any filtration with enough phosphate dosing.

 

[Featherweight]

Has the tank gotten warmer w the season recently?

This is tough, you will get all kinds of info for this.

Me? I'd keep dosing the phos knowing the corals get something. Eventually it will test. Coral health looks good still ... Am I missing anything there?
How's your nitrates level?
Are you dosing any bacteria or carbon for bacteria?

 

[TwelveL16]

I outlined in an article of mine exactly how I would approach filtration for low nutrient tanks:

The Complete Guide to Raising Nutrients

Raising nutrients isn’t always easy; for some systems, it can feel like an uphill battle: confusing, frustrating, and full of contradictory advice. It’s not always clear which products to use, what to dose, or which filtration methods to adjust or remove. Chronically low nutrients are...

www.reef2reef.com

Here’s a breakdown of what’s safe to adjust, and what’s better left in place:

Protein Skimmers
Skimmers should generally remain running. They are not effective at removing nitrate or phosphate directly, and they serve important functions such as removing organics, bacteria, heavy metals, and CO₂, while also supporting oxygen saturation. Removing the skimmer is rarely beneficial and may cause more harm than good.

Bacterial Export (Carbon Dosing, Biopellets, Denitrators)
Bacterial-based filtration methods are highly effective at reducing nutrients, particularly nitrate. If your tank is already running low, it’s often best to reduce or pause these approaches until levels increase. Some modern products, like NP Bacto Balance, include some nutrients in their formulation to help prevent nutrient depletion: a promising compromise in certain systems. Nevertheless, scaling back the dosage is a safe and flexible option when nutrients are trending too low.

Refugiums
Algae-based filtration can be scaled back if desired, but completely removing them is usually not required. A shortened photoperiod is a gentler alternative to reduce export while preserving the pH and oxygen benefits refugiums offer, not to mention the habitat they provide for zooplankton.

Water Changes
You can reduce their frequency or volume, but there’s no need to avoid them completely. Water changes offer benefits beyond nutrient control, and no other method removes organics as effectively. They don’t just dilute: they realign. If an element is too low, the new water brings it up. If it’s too high, the water change brings it down. Over time, this pulls parameters toward the baseline of your salt mix.

Mechanical Filtration (Filter Socks, Floss, Roller Mats)
These have minimal effect on dissolved nutrients and don’t need to be removed. You can keep them for water clarity and detritus control.

Chemical Media (Activated Carbon, Purigen)
These do not significantly affect nitrate or phosphate levels and can remain in the system. Their benefits lie more in water clarity and the removal of organic discoloration or toxins.

Phosphate Removers (GFO, PhosGuard, etc.)
If phosphate is already undetectable or bottomed out, remove these immediately. Continuing to run phosphate adsorbers can starve corals and increase the risk of dinoflagellate outbreaks.

Other Media (Matrix, Bio Bricks, Zeolites)
These have little to no direct impact on nutrient levels and can be left in place without issue.





I would stock up on sodium phosphate. The one linked in the first post is significantly more inexpensive than Brightwell’s and actually has a food grade rating, which is as pure as it gets.


You can easily outcompete any filtration with enough phosphate dosing.

I intend to get the items you suggested but this is what I have on hand so might as well use it. I’ll add the 85ML today or whatever I have left and order the items you suggested. Feels wrong adding this much but I trust ya lol.

Thank you for your help.