How much no3po4 from RedSea should I be adding?

[cards98765]

I am struggling to understand the bottle on how much I should be dousing my tanks with no3po4 by RedSea. The company I am using mentioned I should be dousing the correct amount and to go off what the site says but it confuses me as to what is the correct amount. My tank is a 93 gallon cube and my parameters are;
Alk - 126
pH 7.9
PHOS - 2.8
Ca 375
Mg 1,313
AMMO - 0.0
Nitrite 0.0
Nitrate 85
Tank is about 5 years old.
These parameters are according to AquaSpin. With these parameters how much should I be dousing of no3po4 by RedSea

My other tank's parameters are
150 gal
Alk 171
pH 8.0
PHOS 1.5
Ca 361
Mg 1,417
AMMO 0.0
Nitrite 0.0
Nitrate 42
Tank is about more than 10 years old.

Thanks for helping me out on how much to be adding on these two tanks.

 

[Reefing102]

So looking at the dosage from BRS, it appears the average dosage is about 2ml/25 gallons. Using that as a guide, that would equal out to 7.44ml/93 gallons and 12ml/150 gallons.

That said, I’ve never used no3po4 but have read it’s always better to be on the safer side. Also, take into account your actual water volume. Just because your tank size is 93 and 150, doesn’t mean that’s your water volume as you have rock displacement, substrate displacement, plus sump volume, etc. I hope this helps some!

 

[cards98765]

Thank you

 

[Reefing102]

With that in mind, I would also cut that dosage in half as recommended by Bulk Reef Supply just to see the effect of a half dose