Phosphates with "0" TDS & running gfo through RODI.

[Sphinxj13]

First off i am on well water and incoming tds is around 320ppm and after rodi I am at 0 according to tds meter. I'm having an issue with Phosphates in the tank. Phosphates are being checked via hanna checker. Tank is being dosed daily with phosphate e across 24hrs and still hovering around .23. When I test water I'm getting a reading of between 0.03-0.05. Is it possible Phosphates are still making it thru after 2 mixed bed resin chambers? I'm also curious if anyone has ever run rowaphos as the last chamber or if it's even possible or a good idea?

 

[Pvtgloss]

Following

 

[Miami Reef]

The Di will remove all the phosphate.

There is substantial phosphate bound to the rocks and sand in the aquarium. When you lower the PO4, some of the phosphate detaches from the rocks. It takes a few cycles of this happening before you can achieve your goal PO4.

 

[Sphinxj13]

The Di will remove all the phosphate.

There is substantial phosphate bound to the rocks and sand in the aquarium. When you lower the PO4, some of the phosphate detaches from the rocks. It takes a few cycles of this happening before you can achieve your goal PO4.

Even though I test the water straight from RO line and have P04 show up?
Also I would assume that i would have a massive amount of P04 bound up in the sand and rock since I'm dosing enough phosphate e to lower P04 to .06 and it says constant at across the weeks with maybe 0.01-0.02 flutuation.

 

[Miami Reef]

Even though I test the water straight from RO line and have P04 show up?
Also I would assume that i would have a massive amount of P04 bound up in the sand and rock since I'm dosing enough phosphate e to lower P04 to .06 and it says constant at across the weeks with maybe 0.01-0.02 flutuation.

Hanna phosphate checkers don’t work in freshwater.

How high is the PO4 testing in the new water?

 

[Sphinxj13]

Hanna phosphate checkers don’t work in freshwater.

How high is the PO4 testing in the new water?

Freshly mixed water comes in at 0.04 which is +/- 0.01 difference between the salt & fresh water. I guess it's possible that the hanna checker is off. My concern is that I started up a new 40g tank also with live rock and live sand, none from existing 180 and 5 days later tested P04 just to see and came back at 0.23 which is why I'm wondering if it's possible to have phosphates with 0 tds.

 

[Sphinxj13]

Also is it possible to pack rowaphos in RODI container and run it thru after di resin?

 

[Miami Reef]

Also is it possible to pack rowaphos in RODI container and run it thru after di resin?

I don’t know the exact math, but the phosphate coming from the RO/DI by top off does not even come close to the amount added by foods every day.

@Randy Holmes-Farley can answer if you can use GFO after the Di stage. I hypothesize that Di is more than adequate at removing PO4 as long as the Di is not exhausted.