Making sense of Phosphate readings

[asylumdown]

So after a massive campaign of water changes to try and save my tank, I'm at the point where I'm starting to add some of the reactors and dosing equipment that I took offline back to my system.

The first thing that I added back was my GFO reactor, filled with rowaphos, as I'm finished doing massive water changes every day and I presently have zero nutrient control on the tank.

Using the Hanna ULR kit, 2 days ago I measured P levels of of 29ppb, which when you do the math works out to 0.088ppm PO4, which is higher than I normally like my tank to run at. Right after that I added the GFO reactor back to the system and filled it with Rowaphos. Frustratingly, the next day the ULR kit measured P of 36ppb (0.11ppm PO4) and today it measured 46ppb (0.14ppm PO4).

Is this just my test sucking? How is it possible that my phosphate levels are rising after adding an adsorber? Do I need to put way more Rowaphos in the reactor?

My nitrates have also been steadily increasing since I took the biopellets offline as well. Even with a 60% water change earlier in the week, and 10 20% water changes in the days around that big change, my nitrates have climbed to 1ppm from undetectable. grrrr.

[jordsyke]

I find that in my 45 gallon tank I have the same issues, I beleive that over the years the sand has just grabbed so much crap that it is forever leaching back into my system.... In my 120Gallon I use both biopellets and GFO and find a can easily keep my nitrates at 1ppm which is fine to me, and .06-.15 phosphates which is also an acceptable level in my mind

[asylumdown]

well what's weird is that I've always run GFO and have had very low phosphate for the entire life of the tank. However, I haven't had the ULR test kit for very long, I was using the regular hannah checker which would routinely show me having no phosphate. But now with the ULR kit, I'm not sure if my results are 'real' or if they're the natural variation in responses I'd get from not doing the test exactly the same each time.

[MarkoD]

I have been running zeo for 3 weeks and my phosphates are at .35ppm as per the Hanna checker

[mark]

simple as the Hanna testers are, drift you're seeing could be just errors in testing

[Magickiwi]

Originally Posted by mark

simple as the Hanna testers are, drift you're seeing could be just errors in testing

+1 I think those are pretty good #'s for Hanna testers. They are only advertised +/-5% accurate and I would be very surprised if they are really that accurate.

[Proteus]

I thought I was having po4 issues as my red sea kit was reading upwards of 0.16.
Today I tested against elos and salifert and both showed 0.03 or less

[Wheelman76]

Originally Posted by Magickiwi

+1 I think those are pretty good #'s for Hanna testers. They are only advertised +/-5% accurate and I would be very surprised if they are really that accurate.

Who knows how accurate the checkers really are , however keep in mind that the regular checker is +\-5% ppm , whereas the ultra low range phosphorous checker is +\-5% ppb which is more accurate.

[Myka]

I think people rely a bit too heavily on nitrate and phosphate test results. I think we have a tendency to try to measure and control as many variables as possible, and in this blinding determination we fail to really look at the tank.

You say you filled up the reactor - exactly how much RowaPhos did you use? RowaPhos is quite aggressive. In my experience, too much GFO is much more detrimental than too little (or none). I hope you are adding your equipment back cautiously and "gently".

[Wheelman76]

Completely agree ^^