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.

PS, I’d consider scraping the back wall. It might make the tank look better! Of course, you don’t have to if you don’t want to.

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.