Difference between these phosphate testers?

[Leon Gorani]

I’m looking to buy a phosphate checker but I’m having trouble deciding what to buy. There are three variations in seeing (even though one is out of stock on bulk reef supply).
what’s the difference between these;
- phosphate low range HI713.
- phosphate ultra low range ppm HI774.
- phosphorus ultra low range HI736
So what is the difference between all of these phosphate testers? I think ultra low range give more accurate results than the standard one.
Which is the best to buy?

 

[Ron Reefman]

You should probably try this in the Chemistry forum.

But let's try for some help here first.
#reefsquad

 

[jda]

The low ranges are more fine in the low range. The HI736 is the most fine - you have to do some quick math with this, but it is the one that most people trust and use.

 

[Idoc]

If you have a choice, then go with the ultra low range ppm version. I have had the low range version and then changed to the ultra low range ppb version for greater accuracy at the really low po4 levels. I don't do the math to convert the ppb to ppm but rather cheat and look it up on a website that has already done the conversions.

The low range only had an accuracy of +/- 0.04 ppm. So, a reading of zero could be anywhere between 0.00 - 0.04 ppm which wasn't very much help when I was fighting dinos and monitoring my po4 closely. The ultra low range accuracy is 0.015ppm.

Here's the conversion site to change from ppb to ppm.

Hanna ULR Phosphorus Checker ppb to ppm phosphate conversion chart

 

[saltyhog]

The low range unit is not really appropriate for reef applications. It can fail to detect normal/adequate PO4 levels in reef aquariums.

I like the ULR phosphorous but my Apex auto converts to PO4 when I log my results. If you don't want to do the conversion the ULR phosphate is what you should get.

 

[jda]

For the ultra low phosphorous, you take the number multiplied by 3.066 and then divide by 1000. If this is vexing, then the rest of your reef experience will be too.