Rodi water -what should phosphorus test

ctsps · Feb 10, 2018

So I'm testing my rodi water that I just changed all my filters in December tested at 12ppb

Made up some Fritz pro salt 23ppb

I changed di resin again will test later is this normal

hijinks7 · Feb 10, 2018

try putting some of the exit water right into a glass jar and testing. It might be the container you are using to hold the water leeching into the water. Also make sure the test is for fresh water and not salt if you are testing RODI water.

ctsps · Feb 10, 2018

Thx,I'm asking should it be zero,I did a water change and my phos spiked up,Hanna phosphorus test kit should fresh salt water mix be zero

hijinks7 · Feb 10, 2018

yes if its a good salt.. it should be 0 or very close to it

ctsps · Feb 10, 2018

Ok,I have a prob,thx for your imput,appreciate it

redfishbluefish · Feb 10, 2018

I see you mentioned Hanna Phorphorus tester. If I'm not mistaken, that can not be used for freshwater. Still doesn't explain why you're seeing it in the saltwater sample???

ctsps · Feb 10, 2018

Agree,I got 12ppb fresh,24ppb aft mixing salt,close call on my sps tank,battled thru dinos now this

Randy Holmes-Farley · Feb 10, 2018

ctsps said:
So I'm testing my rodi water that I just changed all my filters in December tested at 12ppb

Made up some Fritz pro salt 23ppb

I changed di resin again will test later is this normal

Those levels are so low as to be no concern whatsoever.

I discuss that here:

Phosphate And Math: Yes You Need To Understand Both
http://www.advancedaquarist.com/2012/3/chemistry

Comparison of Food Sources of Phosphate to Other Sources
What about other sources of phosphate, like the "crappy" RO/DI water containing 0.05 ppm phosphate? A similar analysis will show it equally unimportant relative to foods.

Let's assume that the aquarist in question adds 1% of the total tank volume each day with RO/DI to replace evaporation. Simple math shows that the 0.05 ppm in the RO/DI becomes 0.0005 ppm added each day to the phosphate concentration in the aquarium. That dilution step is critical, taking a scary number like 0.05 ppm down to an almost meaningless 0.0005 ppm daily addition. Since that 0.0005 ppm is 40-600 times lower than the amount added each day in foods (Table 4), it does not seem worthy of the angst many aquarists put on such measurements. That said, tap water could have as much as 5 ppm phosphate, and that value could then become a dominating source of phosphate and would be quite problematic. Purifying tap water is important for this and many other reasons.

Randy Holmes-Farley · Feb 10, 2018

ctsps said:
Ok,I have a prob,thx for your imput,appreciate it

No, you do not have a "problem".

ctsps · Feb 10, 2018

Im just wondering how phosphorus went from 33ppb to 47ppb after a water change,no feeding,at 33ppb i was feeding heavy twice a day, something happened, 1 acro died thats a problem

Randy Holmes-Farley · Feb 10, 2018

ctsps said:
Im just wondering how phosphorus went from 33ppb to 47ppb after a water change,no feeding,at 33ppb i was feeding heavy twice a day, something happened, 1 acro died thats a problem

Probably either test error or you stirred up stuff. The new water itself is not the source, right, since by your own measurements, it is lower than the tank before the change (or after).

That said, 47 ppb phosphorus (as phosphate) is not going to kill a coral. Corals can thrive at far higher levels.

ctsps · Feb 10, 2018

Crazy it was stable at 33ppb,rid myself of dinos,system wasn't using gfo, now I have to hook a reactor up

ctsps · Mar 18, 2018

So I hooked up another di to my rodi system 0 tds in and out,new brute mixing chamber and plumbing ,Fritz pro salt mixing up a 28ppb phosphorus, contacted Fritz they said no way so I'm gonna change salt and see,anyone else check there salt