Dosing Sodium Phosphate

bobnicaragua · Sep 10, 2022

I’ve got a 6” 135 gal sps tank full of small colonies and frags. Even with a robust fish population and skimming dry, my nutrients are usually undetectable.

I started dosing sodium nitrate and sodium phosphate daily a few weeks ago. It’s been tricky getting the phosphates to stay consistent, but things have finally settled in.

Phosphates are .02 ppm in the morning before dosing. I dose 1.1 ppm sodium phosphate daily. Phosphates measure 1.3 an hour after testing, then back at .02 the next morning,

Is this reasonable?

blaxsun · Sep 10, 2022

Possibly. What kind of testing kit are you using?

bobnicaragua · Sep 10, 2022

blaxsun said:
Possibly. What kind of testing kit are you using?

hanna ultra low phosphorus

Miami Reef · Sep 10, 2022

Seems normal. I see a lot of coralline growth, plus rocks and sand that will bind a substantial amount of phosphates. You will need to keep up the dosing of phosphates until it becomes saturated at the level you are targeting.

You’ll get there soon.

bobnicaragua · Sep 10, 2022

I do moonshiners, so I’m dosing multiple trace elements plus phosphates and nitrates daily. Phosphates are tricky to dial in. I wasn’t expecting the daily phosphate dose to be this high.

Randy Holmes-Farley · Sep 11, 2022

Do you really mean you dose 1.1 ppm phosphate?

GarrettT · Sep 11, 2022

0.11ppm in phosphate is common, but not 1.1ppm. That is a very high amount.

bobnicaragua · Sep 11, 2022

Sorry, 0.11 ppm is what I dose daily. 24 hours later it’s back to 0.02

GarrettT · Sep 11, 2022

That is perfectly normal, at least until your rocks and sand reach equilibrium. This can take a long time. I would just continue to dose and monitor until then. Try and keep your skimmers collection cup off or drain valve open if you can.