Could my Hanna checker be off?

[DazAquariums]

So my tank is a little new. Its just under 2 months currently which could be some of the issue but I just want to make sure. Im using the Hanna checker (HI713) to measure PO4 and it has been creeping up week by week. As of today it read .5 ppm which seems a bit high to me.

I feed frozen mysis nightly. Usually a cube last me about a week for the two clowns and other tank mates and I feed about a 1 inch square of dry seaweed to the kole tang daily who consumes it all very quickly.

Nutrient export is a protein skimmer (Bubble Magus Curve 5), 10 gallon weekly water change (5 gallons on Wednesday and 5 on Sunday) and I just started up the refugium. Should I keep this going or possibly switch something up? So far it doesn't seem to be affecting the few coral I have in the tank or the various creatures I have in there as well. Also no advisable algae anywhere on the tank so far and I would like to keep it that way.

60 gallon tank, trigger systems 20c sump
Ammonia 0
Nitrites 0
Nitrates 20 ppm
Phosphates .5 ppm
PH 8.2
Alk 9.5
Calcium 430
Mag 1400

 

[jt17]

If you are using the ULR phosphate checker then you may just be in the .teens. Anything outside of its range results in an elevated reading. Try diluting your sample with RODI and that should bring it into range.

 

[DazAquariums]

If you are using the ULR phosphate checker then you may just be in the .teens. Anything outside of its range results in an elevated reading. Try diluting your sample with RODI and that should bring it into range.

Thank you for the response. I’m not using the ULR checker just the regular low range one.

 

[homer1475]

Easiest way to tell is get the standards and run the test with the standards. If your reading is off from what the standards are supposed to be, then your meter is off and will have to be sent back to @Hanna Instruments

 

[Larry L]

As of today it read .5 ppm which seems a bit high to me.
[...]
So far it doesn't seem to be affecting the few coral I have in the tank or the various creatures I have in there as well. Also no advisable algae anywhere on the tank so far and I would like to keep it that way.

That's not outrageously high, and seems in line with your nitrates, especially if things in the tank look to be doing ok and you are not having algae problems. Seems like a lot of people who feed frozen food regularly, especially mysis, report higher phosphates. There are a lot of successful tanks out there that run into that range. Trying to make changes too quickly will probably cause more harm than good. I'd probably try testing your top off and/or salt mix water just to make sure they are not reading high, and maybe see if a LFS could test a sample for you just to have something to compare to. And maybe like @homer1475 suggested buy the Hanna phosphate calibration standard to make sure your checker is reading ok.

If you are using the ULR phosphate checker then you may just be in the .teens. Anything outside of its range results in an elevated reading.

That's not necessarily true here, 0.5 ppm is right near the middle of the range for the 774 ULR. Any of the checkers get somewhat less accurate at their high ends, but based on manufacturer accuracy specs a reading of 0.5 ppm on the regular 713 could mean an actual value somewhere in the range of 0.44 to 0.56, where the same reading on the 774 ULR could mean an actual value somewhere in the range of 0.455 to 0.545, so basically the same.

http://larryl.emailplus.org/fish/test-kit-calculators.html