Phosphorus vs phosphates

[Pepere]

So macronutrients are Nitrogen, potassium and phosphorus.

 

so, do plants utilize phosphorus differently than phosphates? 
 

if my tap water has 1 ppm phosphates would I still need to dose phosphorus?  Or does it negate the need to add?

 

looking to you @Mmiller2001   @Seattle_Aquarist as well as others deep into the dry ferts mix your own mix….

[Mmiller2001]

https://pediaa.com/difference-between-phosphorus-and-phosphate/amp/#Phosphorous

On 6/15/2023 at 4:53 PM, Pepere said:

macronutrients are Nitrogen, potassium and phosphorus.

Calcium, Magnesium, Sulfur and Carbon.

I believe the plants only want the P (phosphorus), but we dose PO4 (phosphate) probably for solubility issues. But I'm dumb and probably wrong.

[Pepere]

On 6/15/2023 at 7:44 PM, Mmiller2001 said:

I believe the plants only want the P (phosphorus), but we dose PO4 (phosphate) probably for solubility issues.

So if I keep the tank at 1 ppm phosphate, no need to add, correct?

[Seattle_Aquarist]

On 6/15/2023 at 3:53 PM, Pepere said:

So macronutrients are Nitrogen, potassium and phosphorus.

 

so, do plants utilize phosphorus differently than phosphates? 
 

if my tap water has 1 ppm phosphates would I still need to dose phosphorus?  Or does it negate the need to add?

 

looking to you @Mmiller2001   @Seattle_Aquarist as well as others deep into the dry ferts mix your own mix….

Hi @Pepere

Phosphorus is a pure metal which cannot be utilized by plants.  Phosphate is a 'salt' (compound) of phosphorus and another mineral such as potassium, sodium, or calcium just to name a few.  The common form we use in the hobby is a form of potassium phosphate called mono potassium phosphate. 

If your tap water has 1.0 ppm of phosphorus you could add more.  Tom Barr typically has used a ration of 3-4:1 NO3 to PO4 so if you target 20 ppm of NO3 then 5.0 - 7.0 ppm of PO4 should be the target level.  Hope this helps! -Roy

[Mmiller2001]

On 6/15/2023 at 5:55 PM, Pepere said:

So if I keep the tank at 1 ppm phosphate, no need to add, correct?

I think I'm wrong. I'm dosing KH2PO4 and I use PO4 as my target. So go off PO4.

[Seattle_Aquarist]

On 6/15/2023 at 5:07 PM, Mmiller2001 said:

I think I'm wrong. I'm dosing KH2PO4 and I use PO4 as my target. So go off PO4.

Hi @Mmiller2001

KH2PO4 (mono potassium phosphate) is the correct salt.  If you are targeting 5 ppm of PO4 that should result in 2.06 ppm of added potassium (K) then I use K2SO4 (potassium sulfate) to make up the difference to reach 20 - 30 ppm of potassium.  I no longer dose KNO3, K2SO4, or KH2PO4 unless I see a specific need since I have moved over to DIY Osmocote Plus "OO" capsules for the majority of my macro nutrients.  I use Seachem Flourish and my own DIY iron (Fe) mixture of CSM+B, DTPA chelated iron, and ferrous gluconate for my micro nutrients.  -Roy


 

Edited June 16 by Seattle_Aquarist
clarification