RO/DI unit producing high phosphate water

[gobeach]

I was reading the thread about "Brute" containers leaching phosphates so I decide to test my RO water which I store in a Brute container. The RO water was much higher than I thought - I tested twice and got 0.15 both times. Next step, test the water coming out of the unit - even higher - tested twice and got .35 the first time so let the water run for awhile and tested again with a .27 result. Yikes!

I just changed the resin, and recently added a BRS Chloramine monster to the existing 150 Gpd BRS RO/DI unit. I've got replacement cartridges on the shelf, I'll change everything out - my outgoing TDS is at 0.

Any thoughts on the cause?

 

[1fishkeeper]

That's just crazy

 

[gobeach]

I'm using a Hanna test unit and the Reagent does not expire until 8/20/15

I did some more work on the RO/DI unit - changed all 3 canisters, let it run a bit and tested water again - out put is now down to .12 (better but not great).

I just tested the tank, it's at 0.14 today. I tested 5 days ago and got 0.07 - that same day I tested the output of my RO/DI unit and it was at 0.02. Any chance my Hanna kit has got a hitch to it's giddy-up?

I tested the tank with an old API test kit I had on the shelf, the phosphate read at 0.

 

[cginter]

You try a different test kit? That just seems way to abnormal.

 

[Velodog2]

Hanna Checker strikes again ...

 

[AZDesertRat]

Testers do not work well on ultrapure waters.

You are asking a $40-$50 pocket meter to do the job of a $100k lab quality meter on very agressive, unstable pure water and down to parts per billion accuracy and its not going to happen ever.

Use a good handheld TDS meter or conductivity/resistivity meter and forget the testers and test kits. They were never designed to test RO/DI or distilled water no matter what some vendor tells you.
Phosphate (PO4) and your RODI system - Reef Central Online Community

 

[mcarroll]

This is like the third or fourth thread today I think bringing up the mythical po4-in-the-plastic. What gives?

Just to say it again, Brute cans are safe, food-grade LLPE plastic and the Mfgr specifically claims they are unaffected by DI water, so you can sue em if they are wrong.

Can we get this info in a Sticky?

-Matt

P.S. I actually called them this afternoon and got this confirmation. LOL

 

[Velodog2]

It's also interesting to me (although a little off-topic) how people are making RO/DI water out to be somehow "caustic". It is inert. It "pulls" things out because it is so pure it always sets up as large a concentration gradient as can exist, then the laws of thermodynamics take over.

 

[Shtiff1]

This is like the third or fourth thread today I think bringing up the mythical po4-in-the-plastic. What gives?

Just to say it again, Brute cans are safe, food-grade LLPE plastic and the Mfgr specifically claims they are unaffected by DI water, so you can sue em if they are wrong.

Can we get this info in a Sticky?

-Matt

P.S. I actually called them this afternoon and got this confirmation. LOL

Agreed

 

[mike007]

Personally i would not trust the Hanna checker. My experience with them is they will give you a different reading every time you use them. As Dessert Rat said you need a very expensive tester to get accurate results.

 

[gobeach]

Personally i would not trust the Hanna checker. My experience with them is they will give you a different reading every time you use them. As Dessert Rat said you need a very expensive tester to get accurate results.

Mike - what do you use to test your phosphate?

 

[mcarroll]

The Hanna phosphorus meter is definitely more demanding than a manual phosphate liquid test (really applies to all photometers), and many folks have issues getting consistent results right away, but it's not impossible. (Tons of folks use them and love them. Even I did it. The calcium meter is probably the most complicated and I even got that one down pat. ) And to me it's worth repeating - manual liquid tests are arguably no better than watching algae growth in the tank for determining phosphate levels.

Getting good with a photometer is really the only option if you must test for phosphates.

Testing for such low concentrations in pure DI water might be a different story though. I see claims they can and claims they can't - none very authoritative. I'm personally not sure. I would tend to believe Hanna one way or the other if they've made a claim about this. (If I were personally more interested, I'd just call them and ask.) They are the ones with something to lose if they claim their product can do something it really cannot.

-Matt

 

[glb]

The Hanna phosphorus meter is definitely more demanding than a manual phosphate liquid test (really applies to all photometers), and many folks have issues getting consistent results right away, but it's not impossible. (Tons of folks use them and love them. Even I did it. The calcium meter is probably the most complicated and I even got that one down pat. ) And to me it's worth repeating - manual liquid tests are arguably no better than watching algae growth in the tank for determining phosphate levels.

Getting good with a photometer is really the only option if you must test for phosphates.

Testing for such low concentrations in pure DI water might be a different story though. I see claims they can and claims they can't - none very authoritative. I'm personally not sure. I would tend to believe Hanna one way or the other if they've made a claim about this. (If I were personally more interested, I'd just call them and ask.) They are the ones with something to lose if they claim their product can do something it really cannot.

-Matt

Agree. The hanna phosphate checker takes some getting used to but once you get the testing down pat, I think it's better than a lot of the other tests.