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asylumdown
03-28-2014, 05:48 PM
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
03-28-2014, 05:52 PM
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
03-28-2014, 06:23 PM
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
03-28-2014, 06:44 PM
I have been running zeo for 3 weeks and my phosphates are at .35ppm as per the Hanna checker

mark
03-28-2014, 07:18 PM
simple as the Hanna testers are, drift you're seeing could be just errors in testing

Magickiwi
03-28-2014, 09:40 PM
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
03-28-2014, 10:00 PM
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
03-28-2014, 10:23 PM
+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
03-29-2014, 04:22 AM
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
03-29-2014, 04:51 AM
Completely agree ^^

asylumdown
03-30-2014, 11:03 PM
Normally I don't pay much head to nitrate and phosphate tests, and I normally only test the major ions once every couple of weeks. I'm paying extra special attention right now because things were so unbelievably out of whack, and then I took everything offline, so I'm doing all this testing to get things back on track. Once all my systems are back in place and my auto-dower is dialled in I'll probably go back to hardly ever testing.

And I'm going to stop trusting my hanna checker. With the rowaphos in there (and I used about 15-20% of the amount I would normally have put in if it was just regular bulk GFO), I was seeing a steady climb every day. I changed out the Rowaphos last night because I thought that maybe with such a small amount in the reactor it had honestly already been exhausted, but this morning it measured 0.21 after the conversion to PPM Phosphate, which shouldn't be possible unless the Roawphos was actually contributing phos rather than removing it. I've been using the same glass vial for each test though, and right after I got the 0.21 result, I swapped out the vial for one of the vials from my calcium kit and got a result of 0.008ppm phosphate.

I think my vial has been getting imperceptibly stained by each sequential test. I gave it a thorough wash with a bottle brush cleaner and laboratory soap two days ago, and I empty and rinse the vials with distilled water immediately after each test, but it's apparently not enough. I don't know how else to clean it, and it looks spotless to my eyes, but when one vial gives you 0.21ppm and another vial gives you 0.008 with the same water following the exact same protocol, it makes me not trust any of the results if the equipment alone can contribute such a wide margin of error.

As for the nitrate tests, today it was 2ppm. It's been a clear and steady increase since I took the pellet reactor offline and stopped doing massive daily water changes. More than anything I think it's just interesting to see, as my tank has never not had pellets on it so I really had no idea what it would do without them. I don't necessarily trust the numbers exactly, but I do trust the relative colour development which indicates that my nitrates are definitely rising. The Red Sea nitrate kit uses the same reagent protocol as my faculty's analytical hydrogeology lab (which really means it shouldn't be going down the sink as there's cadmium in it, but Red Sea doesn't tell you that), and while my lab would use a Hach spectrophotometer to measure the colour exactly, you can get a really good qualitative idea of the amount of nitrate in the sample just by looking at how red/pink it turns. And every day since wednesday my sample has been progressively pinker than the day before.

Magickiwi
03-31-2014, 03:18 PM
Normally I don't pay much head to nitrate and phosphate tests, and I normally only test the major ions once every couple of weeks. I'm paying extra special attention right now because things were so unbelievably out of whack, and then I took everything offline, so I'm doing all this testing to get things back on track. Once all my systems are back in place and my auto-dower is dialled in I'll probably go back to hardly ever testing.

And I'm going to stop trusting my hanna checker. With the rowaphos in there (and I used about 15-20% of the amount I would normally have put in if it was just regular bulk GFO), I was seeing a steady climb every day. I changed out the Rowaphos last night because I thought that maybe with such a small amount in the reactor it had honestly already been exhausted, but this morning it measured 0.21 after the conversion to PPM Phosphate, which shouldn't be possible unless the Roawphos was actually contributing phos rather than removing it. I've been using the same glass vial for each test though, and right after I got the 0.21 result, I swapped out the vial for one of the vials from my calcium kit and got a result of 0.008ppm phosphate.

I think my vial has been getting imperceptibly stained by each sequential test. I gave it a thorough wash with a bottle brush cleaner and laboratory soap two days ago, and I empty and rinse the vials with distilled water immediately after each test, but it's apparently not enough. I don't know how else to clean it, and it looks spotless to my eyes, but when one vial gives you 0.21ppm and another vial gives you 0.008 with the same water following the exact same protocol, it makes me not trust any of the results if the equipment alone can contribute such a wide margin of error.

As for the nitrate tests, today it was 2ppm. It's been a clear and steady increase since I took the pellet reactor offline and stopped doing massive daily water changes. More than anything I think it's just interesting to see, as my tank has never not had pellets on it so I really had no idea what it would do without them. I don't necessarily trust the numbers exactly, but I do trust the relative colour development which indicates that my nitrates are definitely rising. The Red Sea nitrate kit uses the same reagent protocol as my faculty's analytical hydrogeology lab (which really means it shouldn't be going down the sink as there's cadmium in it, but Red Sea doesn't tell you that), and while my lab would use a Hach spectrophotometer to measure the colour exactly, you can get a really good qualitative idea of the amount of nitrate in the sample just by looking at how red/pink it turns. And every day since wednesday my sample has been progressively pinker than the day before.

I use muriatic acid to wash my sample cuvettes. And I also think that they get stained after a few tests so that you can't trust the readings. I've dosed the Carib-Sea phosbuster twice in the last two weeks and according to the hanna checker my phosphate didn't go down at all the day after etc.

asylumdown
03-31-2014, 05:40 PM
Well I did some digging to try and figure out what product from the Hanna reaction could be staining the glass vials and found this from the EPA methods manual on determining phosphate using the Ascorbic acid method that I'm pretty sure Hanna is using. (http://water.epa.gov/scitech/methods/cwa/bioindicators/upload/2007_07_10_methods_method_365_3.pdf):

6.2 Acid Washed Glassware: All glassware should be rinsed with hot 1:1 HCl and rinsed with distilled water. The acid-washed glassware should be filled with distilled water and treated with all reagents to remove the last traces of phosphorous that might be adsorbed on the glassware. Preferably, this glassware should be used only for the determination of phosphorous and after use it should be rinsed with distilled water and kept covered until needed again. If this is done, the treatment with 1:1 HCl and reagents is only required occasionally. Commercial detergents should never be used.

What I take away from this is that the glass itself can adsorb some P and because of this I should not have rinsed my vials in tap water (I usually rinse in tap first, then finish with a rinse in distilled), I should not have used soap (even though it was lab soap), that there is some product of the reaction that will eventually need to be cleaned with an acid wash (possibly calcium sulphate based on other readings), and that the P from your sample can get adsorbed in to the glass over time.

It's probably not a big deal for the high range checker, but since this checker is measuring in the parts per billion, even a small amount of contamination could throw off the results. The fact that we only use a single powder pillow means that Hanna must have combined the molybdate and tartrate with the ascorbic acid in a single package. An analytical lab would store those separately, but perhaps that's why there's a 2 minute dissolution period before you start your 3 minute reaction timer.

lastlight
03-31-2014, 06:17 PM
so loosely translated i should just go back to watching for increased growth in my chaeto and swap my gfo then? :biggrin:

asylumdown
03-31-2014, 06:32 PM
so loosely translated i should just go back to watching for increased growth in my chaeto and swap my gfo then? :biggrin:

yah I think that's as good a method as any. I'm not sure how many hobbyists have the set up to safely do a wash with hot 1:1 HCl. We also are only measuring orthophosphate with our tests, so a teeny weeny amount of the P moving through our systems.

Don't get me wrong, I think there's value in knowing your orthophosphate concentrations, as having a high concentration of dissolved orthophosphate is as problematic as having no detectable orthophosphate but luxuriant and uncontrolled growth of problem algae, but I think we have to take the results from those tests with a gigantic grain of (sea) salt. Hanna has given us the spectrophotometer necessary to view P down to the ppb range, but for consistently accurate results you also need the analytical lab procedures called for at that resolution. If we were being really picky about it, we'd also want to centrifuge our sample first to make sure there was no microscopic particulates in the solution, but I doubt many hobbyists are going to run out and pick up a $10,000 centrifuge any time soon (even though they're freaking awesome).

If you're changing your GFO with any regularity, your orthophosphate concentration is going to be low, but that doesn't mean that your system's total P load will be low, and P will still be moving through the biological systems in your tank in ways you'll never be able to test for as a hobbyist, so it's really only one component of the whole tank maintenance thing.