More RODI Help

[DSlater]

Getting frustrated here.

Had phosphates in my RODI water a few months back so I ordered new filters, membrane and DI resin... Had been a while. All installed about 6 weeks ago.
Still having PO4 issues so I measured again and it was 0.10ppm on a hanna checker. Lines were flushed clear before taking sample water.
RODI is 4 stage. 1 micron sediment, 1 micron carbon block, RO membrane, then DI resin. I talked to the city of Nanaimo water manager they only add chlorine to our water, where we live should rarely see over 0.5ppm. They dose chlorine to 1.7ppm but we are near the end of a large distribution run. For the same reason turbidity should be low where we live as well, he went into seasonal specifics but lost me quick...

oh... and inline TDS meter reads 10 to 12(guessing ppm) going in and 0 coming out. Says it came factory calibrated.

Am I missing something really obvious here? Any suggestions would be appreciated.

Thanks. Jesse

[e46er]

maybe the hanna checker isnt reading accurately?
how old is the powder?

[DSlater]

I use that hanna checker weekly on two tanks. Reagent box I'm on had an expiry date of 2016.
I did get a box of reagent that would only give out 0.00 readings but both tanks have been in the .12 to .08 range since summer so I'm pretty confident with the readings.

[rayjay]

Sample water taken before the RO, after the RO and before the DI and after the DI. This will tell you where the problem is in the RODI system if indeed it is a problem in that system, it just means disconnecting a couple of places temporarily for the samples.
Best done after the RODI is running for about a half hour or more.
I'd still be checking the phosphates with another test kit.

[DSlater]

Straight tap water - 0.16ppm
After filter and carbon filter - 0.19ppm
After RO membrane - 0.13ppm
After DI Resin - 0.13ppm
Rejected water from RO membrane - 0.25ppm

These results would be believable if filters were old and resin was spent but all are new.

Went to another reefers house today and did some testing. His Salifert PO4 test kit read 0.00ppm on his clean RODI water, my hanna tester read 0.16ppm.

OK, now that I don't trust my meter I came home, opened a new box of reagent and tested tap water for kicks... 0.00pm

What other test kits do people use(and recommend) for PO4?

[Aquattro]

I've always used Hanna, never not trusted what it told me. My reagent is the same batch yours was. If I read 0.1 and do a 50% water change, it says ~0.05.

[Frynoodle]

Beside the hanna checker and TDS metre, is there any algae problem over your tank? If not, why you worry about it?

[DSlater]

Originally Posted by Frynoodle

Beside the hanna checker and TDS metre, is there any algae problem over your tank? If not, why you worry about it?

Have had algae problems in the past but tank looks good now. Just adding new corals and would like to see how they react as parameters change a bit. Also helps with my OCD needs...