Keep dosing sodium phosphate but isn't going up.

fr3n0z · Nov 17, 2022

Hi guys, i wanted to dose no3 and po4 since they we're always to 0 (chaeto reactor or rocks eating it i tink, tank is 4 months, dead rocks).

I have a question, i am dosing sodium nitrate and sodium phosphate following James Planted Tank calculator.

I remember that @Randy Holmes-Farley said that using sodium phosphate will be somewhat lighter compared to potassium phosphate but safer since no potassium in it. But, there is a way to know how much lighter?

did the test monday night and was 0.05, just after i have dosed 0.2ppm. Tuesday night tested and still 0.05 and dosed other 0.2ppm, wensday night tested, 0.1 and did not dose. Tonight tested seems between 0.1 and 0.05 and dosed other 0.2.

I will test tomorrow morning since i don't believe po4 are going down that fast and hope to see it above 0.1

I am always double testing with Tropic Marine and JBL test

Tank is 10g and lightly populated. Chaeto reactor. At night i am dosing since 3 days CACO3 (coral snow)

Randy Holmes-Farley · Nov 17, 2022

Most of the phosphate may be binding to rock and sand surfaces. You may need to dose a lot more.

fr3n0z · Nov 17, 2022

Randy Holmes-Farley said:
Most of the phosphate may be binding to rock and sand surfaces. You may need to dose a lot more.

dosing CACO3 can lower also nitrate and po4? i will up the dosage to 0.4 day and hope it will change. i'm just scared that those colorimetric test they do not work so well

...finger crossed. Thanks for the answer!

Tathamet · Nov 17, 2022

I’m basically on the same boat as you. same tank age as well on my new tank with dry rock (seeded with some 4 year old live rock) and had been dosing 0.2ppm a day as well (in the process of upping it more currently). I test around 8 pm and I always got a reading of 0.00-0.01ppm on my Hanna ulr phosphate checker with the 0.2ppm dose per day.

which brand test kit are you worried about?
comparing my Red Sea phosphate pro test to the Hanna ulr checker seemed pretty consistent with each other.

fr3n0z · Nov 17, 2022

Tathamet said:
I’m basically on the same boat as you. same tank age as well on my new tank with dry rock (seeded with some 4 year old live rock) and had been dosing 0.2ppm a day as well (in the process of upping it more currently). I test around 8 pm and I always got a reading of 0.00-0.01ppm on my Hanna ulr phosphate checker with the 0.2ppm dose per day.

which brand test kit are you worried about?
comparing my Red Sea phosphate pro test to the Hanna ulr checker seemed pretty consistent with each other.

i am using tropic marine and jbl. but what you are telling me and the fact that you are using a hanna checker it makes me more confortable in upping the dosage a bit. thanks

Randy Holmes-Farley · Nov 18, 2022

fr3n0z said:
dosing CACO3 can lower also nitrate and po4? i will up the dosage to 0.4 day and hope it will change. i'm just scared that those colorimetric test they do not work so well ...finger crossed. Thanks for the answer!

Dosing particulate CaCO3?

It may have a phosphate effect by direct binding, but no immediate nitrate effect. Nitrate does not attach to calcium carbonate.

Randy Holmes-Farley · Nov 18, 2022

fr3n0z said:
i am using tropic marine and jbl. but what you are telling me and the fact that you are using a hanna checker it makes me more confortable in upping the dosage a bit. thanks

As I indicated, it is normal to need to dose WAY more than calculated to bring up phosphate. The only utility to a calculation is to be sure you aren't over or underdosing by vast magnitudes.

jda showed that it can take many ppm to bring up phosphate to 0.1 ppm if there is enough bare rock around.

fr3n0z · Nov 18, 2022

Randy Holmes-Farley said:
As I indicated, it is normal to need to dose WAY more than calculated to bring up phosphate. The only utility to a calculation is to be sure you aren't over or underdosing by vast magnitudes.

jda showed that it can take many ppm to bring up phosphate to 0.1 ppm if there is enough bare rock around.

yeah i remember you already adviced on the fact that was needed more...but i tought like it was in the range of .1/.2extra ppm...here it seems to go on the Xppm zone. Anyways probably also the fact that i am dosing CACO3 just a couple hours after dosing PO4 (it is still quite cloudy from caco3) can also be a culprit.

No3 dosing i have no problem tough. On test they show up.

So if i understand correctly i have to saturate rocks and substrate and then it will start to show on test. But is it a good thing to do? Once rock saturate they will start to release po4 and i could end with inverse problem? (po4 too high)

Randy Holmes-Farley · Nov 18, 2022

Saturate is not technically the right word, but you need to add as much as that rock and sand can hold at the equilibrium concentration in the water that you want to attain.

Nitrate has no such binding effect.