Should I get the Phosphurous Checker?

[asylumdown]

Originally Posted by tytown

Just started measuring with Hanna ULR unit but have trouble getting the same reading twice. I've almost gone through a pack of reagent performing multiple measurements between my fresh, mix, and tank water. For example, tank readings were 57, 107, 35 (0.17, 0.32, 0.10 ppm), so I'm pretty much calling BS on this unit unless I'm doing something completely wrong... It's supposed to accurate to +-5% of its range so that's +-10 PPb or 0.03 ppm.
Does anyone get consistent readings close to the units rated accuracy???

nope. Never once. Thought it was me, then I looked in to it. Testing at that resolution outside of an analytical lab is about as accurate as guessing your level by throwing darts at chart.

To be consistent at that sensitivity, you'd need to be measuring the volume of your sample with a micro-pipette, using a fresh pipette every time you collected the sample. You'd also need to be getting the exact same amount of reagent out of the powder pillow every single time (which you never are). You'd also need to be washing your sample cuvette in hydrochloric acid every couple of tests, only ever rinsing the cuvette out in the purest of DI/distilled water, and doing dummy tests with DI/distilled water before each test, as tiny amounts of phosphate can bind to the glass.

You'd also need to be collecting your samples from the exact same spot, at the exact same time, after following the exact same routine. Even dipping your hand in to the water at the time you collect the sample could throw off the results enough to make the number meaningless.

It's why I prefer the regular PO4 kit. It's not as sensitive, and the numbers still need to be viewed as relative rather than absolutes, but at least it's more consistent from reading to reading and gives you a better sense of the actual trend in your tank. When one result is 0.10 and the next one 5 minutes later is 0.32, you have spent 15 minutes obtaining no useful information.

[Aquattro]

I use the regular unit, and for 4 years I consistently got 0ppm. Which was what I wanted to see. Good enough for me. I have an Elos kit, I can't tell if it's 0.01, 0.1, 42.8, etc. Might be my eyes

[asylumdown]

+1. I use the regular unit as well. It's the ULR unit that I think is better suited as a pez dispenser.

[Aquattro]

Originally Posted by asylumdown

+1. I use the regular unit as well. It's the ULR unit that I think is better suited as a pez dispenser.

Nah. I've got a Batman pez dispenser, way better!

[tytown]

Agree on the Elos PO4 kit, that thing is a total waste of money.
So Wheelman and Craig, what are some typical values your phosphorus checker reads? And what do you expect it to read when you test?
Running GFO I would hope to see 10 and below but going by their rated accuracy there's no way I guy can even rely on that.
Just trying to gauge peoples phosphates and their expected reading from their ULR phos checker....
Thanks for all the replys so far

[Craigdillman]

Well for example last week my reading was 0.06 and this week (water change week and GFO change time) it was 0.09 so it just started to rise

[lastlight]

i previously owned the regular tester and always got zero which i never believed. i certainly had algae which apparently IS possible with real zero readings lol. i now use the ULR and for a while i couldn't get back-to-back consistent readings.

now i do a few things that seemed to have made testing reliable and i now like the device:

- only use one of the glass containers. zero the unit and add reagent to same one. avoid differences in glass/scratches etc between containers.

- store ro/di in container between uses then rinse well before use

- made a decent paper funnel to ensure i can more accurately get all or almost all the reagent into the container

- always rotate the glass to the same orientation in the device

[Craigdillman]

I have the hanma one with ppb love it seems to get fairly constituent reading but mostly I use it to test before after after GFO so I know when to replace it test before WC and once a week I can see p04 rising and sometime I need to change out gfo between WC others not. Honestly I couldn't handle trying to read what color off hue blue was which so opted for it

Just my 2 cents