RO/Di resin = PO4?

[specialk]

So I am in a mad search looking for pesky phosphates and trying to rid my tank of them. In all my research I have been doing tonight, I read many times that one should check their RO/Di system.

So I did .. and while i do not have a hanna checker (lost mine .. am going to order a new one if I cant find it) I am doing the generic test and from my estimation the reading is about 0.10 .. all I know is that it is NOT 0!

I have a barracuda 4 stage system and all things have been updated within the last 6 months. My TDS reading are between 0-3. The one thing I will say, is that when my resin expired and went bad about 3 weeks ago, I changed out only half of the old resin and put in half of the new stuff...

.......could this old resin be leaching phosphates and causing these PO4 readings?

 

[Sabellafella]

Ive had 3 tds read 1.0ppm phosphate at times, maybe?

 

[specialk]

Also, just tested my regular tap water just to make sure the testing kit (once again all be it NOT the hanna checker) is not bad, and the reading was drastically higher then when I tested with the ro/di water. So while the ro/di system is working, clearly it is NOT taking out all the phosphates. This appears to be where some of this PO4 is coming from ... so while I feverishly work to rid it from my tank, I am at the same time putting it right back in it seems.

But is it from the older resin ... hmmm... anxiously awaiting an expert on here who maybe experienced this already.

 

[Randy Holmes-Farley Verified Community Expert]

So I am in a mad search looking for pesky phosphates and trying to rid my tank of them. In all my research I have been doing tonight, I read many times that one should check their RO/Di system.

So I did .. and while i do not have a hanna checker (lost mine .. am going to order a new one if I cant find it) I am doing the generic test and from my estimation the reading is about 0.10 .. all I know is that it is NOT 0!

I have a barracuda 4 stage system and all things have been updated within the last 6 months. My TDS reading are between 0-3. The one thing I will say, is that when my resin expired and went bad about 3 weeks ago, I changed out only half of the old resin and put in half of the new stuff...

.......could this old resin be leaching phosphates and causing these PO4 readings?

That is largely a myth, IMO. People measure a tiny bit of phosphate in their RO/DI (which may be real in some cases, and testing error in others) and go bonkers for no sane reason.

The primary source of phosphate is ALWAYS food, unless you are using straight tap water or RO/DI with a totally depleted DI resin. Unfortunately, many people just do not understand the issues around phosphate sources.

I show it mathematically here:

http://www.advancedaquarist.com/2012/3/chemistry

from it:

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.

 

[specialk]

That is largely a myth, IMO. People measure a tiny bit of phosphate in their RO/DI (which may be real in some cases, and testing error in others) and go bonkers for no sane reason.

The primary source of phosphate is ALWAYS food, unless you are using straight tap water or RO/DI with a totally depleted DI resin. Unfortunately, many people just do not understand the issues around phosphate sources.

I show it mathematically here:

http://www.advancedaquarist.com/2012/3/chemistry

Randy YOUR THE MAN ! Such a asset to this forum! And that is going to be my night time read! Going to dive into that right now, but what you said just in that snippet makes a ton of sense! Thanks Randy !!!

 

[Randy Holmes-Farley Verified Community Expert]

Ive had 3 tds read 1.0ppm phosphate at times, maybe?

IMO, that is probably testing error.

How could that happen?

Even with no DI at all, phosphate is rejected by RO membranes at 95+ %.

http://www.watertreatmentguide.com/Membrane_Rejection.htm

So you'd need to start at more than 20 ppm phosphate in the tap water (it doesn't get that high), and then you'd have to explain how you get everything else so low without a DI. The only way i can see is high phosphate/low TDS tap water, which is not very common.

 

[Randy Holmes-Farley Verified Community Expert]

Randy YOUR THE MAN ! Such a asset to this forum! And that is going to be my night time read! Going to dive into that right now, but what you said just in that snippet makes a ton of sense! Thanks Randy !!!

You're welcome.

Pop back for any for any further discussion that is required.

 

[specialk]

tap water[/URL] 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.

But I guess my only follow up question to that would be ... what if I am doing weekly water changes and adding a significant amount of water 15-20% during that change ...(to a 135 gallon system) thus adding phosphates at a bigger clip. Is this still not going to make that much of a difference?

 

[Randy Holmes-Farley Verified Community Expert]

But I guess my only follow up question to that would be ... what if I am doing weekly water changes and adding a significant amount of water 15-20% during that change ...(to a 135 gallon system) thus adding phosphates at a bigger clip. Is this still not going to make that much of a difference?

It will add some, if the measurement is accurate. Still not as much as likely comes from the food that same day (not to mention every other day when foods add it and the water change does not).

It is certainly a fine thing to try to lower it if it is accurate (say, with two DI resins in series), but I would not expect to notice big effects in the aquarium itself.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, there's a big difference between 0 ppm TDS and 3 ppm TDS.

I'd replace the DI as soon as the TDS rises, if for other reasons (ammonia, silicate, etc.).

 

[Sabellafella]

IMO, that is probably testing error.

How could that happen?

Even with no DI at all, phosphate is rejected by RO membranes at 95+ %.

http://www.watertreatmentguide.com/Membrane_Rejection.htm

So you'd need to start at more than 20 ppm phosphate in the tap water (it doesn't get that high), and then you'd have to explain how you get everything else so low without a DI. The only way i can see is high phosphate/low TDS tap water, which is not very common.

Forgot to add that my city water contains 3ppm or more according to salifert test. My tds comming in is only 30-42. My tds out of the membrane is 0-3 and I will get a completely blue hue before the di for phosphate. To be honest theres a big jump in the difference in color so i cant really tell exactly, but ive had an exhausted di resin that was giving out 1ppm or more p04 before

 

[Randy Holmes-Farley Verified Community Expert]

Forgot to add that my city water contains 3ppm or more according to salifert test. My tds comming in is only 30-42. My tds out of the membrane is 0-3 and I will get a completely blue hue before the di for phosphate. To be honest theres a big jump in the difference in color so i cant really tell exactly, but ive had an exhausted di resin that was giving out 1ppm or more p04 before

Yes, when the DI exhausts, phosphate will certainly rise if the DI is loaded with it.

 

[specialk]

ok dumb question here... how do I know IF the GFO is out and done? Will it be a certain way or changed in structure or feeling or anything?

 

[KingTriton]

Honestly its a guess IMO. I use the Hanna Phosphorus 736 to measure my Po4 levels.

My tank water is 0ppm, but my GFO output measures .02ppm while only being 3 days old... I just don't find these test overly accurate. It also shows my Po4's NSW at 0.05ppm with a fresh DI silica-buster cartilage being used.

I personally just monitor the algae on the aquariums glass to give me a good indication.

 

[sghera64]

I buy the notion that food is such a large contributor of phosphate, dwarfing RO water contributions, that I removed my DI cartidge. I use RO (no DI) and I do carbon dosing. My Hanna checker routinely shows less than 10 ppb-Phosphorous in my tank water and I feed my fish well and do 15-20% water changes e/o week.

 

[Cory]

Food shouldn't add po4 until its broken down by bacteria. Thats my understanding and it may be wrong. When the bacteria break it down it adds po4 to the water. But food just added does not add po4.

However beware supermarket shrimp contains lots of po4 as a preservative. That doesn't need to bebroken down to raise po4.

 

[Randy Holmes-Farley Verified Community Expert]

Food shouldn't add po4 until its broken down by bacteria. Thats my understanding and it may be wrong. When the bacteria break it down it adds po4 to the water. But food just added does not add po4.

However beware supermarket shrimp contains lots of po4 as a preservative. That doesn't need to bebroken down to raise po4.

I agree. I'd just add one clarification that some other people may misunderstand. In terms of phosphate release from food, it doesn't really matter if it is consumed by fish, corals, or bacteria. It is still mostly released to the water. If an adult fish eats the food, ALL of the phosphate in it is released to the water.

 

[Cory]

I agree. I'd just add one clarification that some other people may misunderstand. In terms of phosphate release from food, it doesn't really matter if it is consumed by fish, corals, or bacteria. It is still mostly released to the water. If an adult fish eats the food, ALL of the phosphate in it is released to the water.

Is that because of stomache acids breaking the food down, or bacteria in the intestine? Or some other mechanism.

 

[Randy Holmes-Farley Verified Community Expert]

Is that because of stomache acids breaking the food down, or bacteria in the intestine? Or some other mechanism.

It is because the fish, just like people, break down the phosphate from the organic chemicals that are being digested, and there's no net accumulation phosphate in an adult, so what goes in must come out. Most of that happens in the GI tract, and some systemically (meaning elsewhere in the body).

In a human, most of the phosphate consumed comes out in the urine and a smaller amount in the feces. Not sure on a fish how exactly the phosphate is primarily excreted, but balance studies (in vs out) show it does come out. Even in growing juvenile fish, most of it is excreted.

 

[Cory]

It is because the fish, just like people, break down the phosphate from the organic chemicals that are being digested, and there's no net accumulation phosphate in an adult, so what goes in must come out. Most of that happens in the GI tract, and some systemically (meaning elsewhere in the body).

In a human, most of the phosphate consumed comes out in the urine and a smaller amount in the feces. Not sure on a fish how exactly the phosphate is primarily excreted, but balance studies (in vs out) show it does come out. Even in growing juvenile fish, most of it is excreted.

Interesting. So over feeding means something new here. Basically food doesnt have to be broken down by bacteria once it passes through the fishes digestive system to release po4 into the tank water. Correct?

The old 1 inch of fish per gallon rule, or whatever it was, isnt only for ammonia then but po4 too.

Sorry to hijack this thread a bit