Po4 Dosing

[link81]

looking into dosing phosphates to bring them up to a detectable level.
I have a spare 1.1 dosing pump that i'll be using. Plan on mixing up my own solution.
is there a reason to use MSP DSP or TSP over one another?
are there any calculators i can use to get a starting point? i.e max solubility of phosphate into DI water, and how much added will raise po4 X amount per gallon of water?

I saw somewhere @Randy Holmes-Farley recommended something similar to this:

https://www.amazon.com/Disodium-Phosphate-FOOD-GRADE-Purity/dp/B013TQVSVQ

or this (i like that this is US made)

https://www.amazon.com/TriSodium-Ph...te+food+grade&qid=1560969442&s=gateway&sr=8-2

if it works, great i'll use it, now i need to figure out what ratio to mix it at, and a good starting place for dosing.

I have a gallon dosing container, so i'm planning on mixing it up at near full solubility in 1 liter batches.

 

[sghera64]

FWIW, I use TSP. I did my own calculations assuming it was about 95% pure and not hydrated. Dosing based on math/chem gets you close, then you have to kind of titrate your dose setting.

Go slow, there can be a delayed response as the system has a lag on its ability to take up phosphate (and nitrate for that matter).

 

[ravi197699]

what is the recipe for to dose nitrate and phophates? sorry new to this and I having dino issues and need to raise the phosphates and nitrates..

 

[link81]

@sghera64
Thanks, any idea where you started as far as tsp concentration and initial dose?

 

[Gareth elliott]

https://rotalabutterfly.com/nutrient-calculator.php

I like to use this, i prefer NaNO3 simply because its almost identical to KNO3 in how much NO3 is added.

Phosphate i use KH2PO4 since i can use the exact calculations as well.

NO3 is easier to dose with math PO4 there is so much binding that occurs that have to test a lot more.

 

[sghera64]

@sghera64
Thanks, any idea where you started as far as tsp concentration and initial dose?

Sure, I’m including a pic of my calcs from my notebook.

Bottom line, I did assume that the TSP (Na3PO4) is 100% pure. Not true, but good enough to get a mathematical start. I make up a 1 Liter stock solution with 1.33 grams of TSP added to 1L of water. If I add 10 mL of this to my 800L system, it should raise the PO4 level by 0.010 ppm.

You can use ratios to make that work for your system by taking the volume of your system (say 400L) divided by my 800L and multiplying that by 1.33 grams. The result is how many grams you would add to 1L of water. Then, if you add 10mL of that to your system, it should raise the PO4 level by 0.010ppm.

I did this 10mL addition e/o day at first until I began to get readings on my Hanna ULR. Than I adjusted the amount as I switched to daily doses. The tank will consume a certain amount and there will be error in how much you think you are adding. In the end, you find your daily dose. In my case, after a number of weeks, I had to back off the PO4 and eventually stopped adding all together. I think the system simply found its balance.

 

[link81]

that is awesomely helpful. thanks a ton. I have a hanna ULR on the way, I'll get a gram scale and some TSP ordered up from amazon. I'm probably about 200L so it will be super easy to resolve the ratio and go from there.

Thanks again!

 

[link81]

TSP, a gram scale, and graduated cylinders are on the way.
hopefully can start dosing this weekend.

 

[link81]

one more question,
is it better to dose po4 multiple times throughout the day? or should it all in one shot?

 

[ravi197699]

in my opinion it is always better to brake down the dosage for period of time, it is much safer especially when dosing phosphates, slow rise is always better than sudden swing...