Inconsistent nitrate test results lately

[Ryan15236]

Looking for some insight on some inconsistent nitrate readings I have gotten lately.

Tank is 15 months old. 180 gallon mixed reef. Stocking D. Sailfin tang, Hippo tang, convict tang, purple tang, foxface, CBB, longnose Hawk, melanarus wrasse. Went thru ugly stages seemed to last forever. Still lingering cyanobacteria in some places. During ugly stages just focused on manual removal until tank started stabilizing. I have been getting results for about 2 months of 20-25 ppm. 2.5 weeks ago I tested and results showed 41ppm so did 20G WC and test results after showed 23ppm (10/18). After that WC I started focusing on changed filter socks more often. I run two filter socks on my trigger sump and I will change out the sock closest to water inlet into sump when overflowing (roughly every 3 days) and then move the other sock up a slot into that socks previously slot and new sock replaces the sock I just moved up slots. So changing out 1 sock every 3 days. Have not done water change since 10/18 so I test yesterday and got 0.4 ppm so I added 1 ML of sodium nitrate solution (50G dissolved in 480 ml RODI water) just to prevent zero. so I retested this morning 10/28 and got a maxed out 75PPM then retested again and got 3.7PPM. Yesterday I used about a tube of JB waterweld placing about 15 corals. Could this be messing with results? Also I am testing from sump return which is also where ATO water goes. Could this water be interfering with results? I do not pull sample when ATO is running. The 3.7 PPM result sample I pulled from refugium. Testing is done with Hanna Checker Nitrate HR.

 

[BryanM]

With that much inconsistency I wonder if you've got a bad batch of reagents.

I've personally been the recipient of one bad batch about 6 months or so ago, though they all tested very low, didn't bounce around.

I don't think JB Weld is the issue.

 

[Ryan15236]

With that much inconsistency I wonder if you've got a bad batch of reagents.

I've personally been the recipient of one bad batch about 6 months or so ago, though they all tested very low, didn't bounce around.

I don't think JB Weld is the issue.

Not sure how often that happens but this is a new batch of reagent. I ordered this batch 10/14. Probably had a couple of my old left but definitely been using this new batch during the last 4 tests

 

[Ryan15236]

With that much inconsistency I wonder if you've got a bad batch of reagents.

I've personally been the recipient of one bad batch about 6 months or so ago, though they all tested very low, didn't bounce around.

I don't think JB Weld is the issue.

The blinking 75 ppm test blew my mind. When I added Reagent to sample it almost instantly turned a dark red

 

[Dan_P]

Looking for some insight on some inconsistent nitrate readings I have gotten lately.

Tank is 15 months old. 180 gallon mixed reef. Stocking D. Sailfin tang, Hippo tang, convict tang, purple tang, foxface, CBB, longnose Hawk, melanarus wrasse. Went thru ugly stages seemed to last forever. Still lingering cyanobacteria in some places. During ugly stages just focused on manual removal until tank started stabilizing. I have been getting results for about 2 months of 20-25 ppm. 2.5 weeks ago I tested and results showed 41ppm so did 20G WC and test results after showed 23ppm (10/18). After that WC I started focusing on changed filter socks more often. I run two filter socks on my trigger sump and I will change out the sock closest to water inlet into sump when overflowing (roughly every 3 days) and then move the other sock up a slot into that socks previously slot and new sock replaces the sock I just moved up slots. So changing out 1 sock every 3 days. Have not done water change since 10/18 so I test yesterday and got 0.4 ppm so I added 1 ML of sodium nitrate solution (50G dissolved in 480 ml RODI water) just to prevent zero. so I retested this morning 10/28 and got a maxed out 75PPM then retested again and got 3.7PPM. Yesterday I used about a tube of JB waterweld placing about 15 corals. Could this be messing with results? Also I am testing from sump return which is also where ATO water goes. Could this water be interfering with results? I do not pull sample when ATO is running. The 3.7 PPM result sample I pulled from refugium. Testing is done with Hanna Checker Nitrate HR.

Since the nitrate test results were incorrect after the water change, something is up with the nitrate test. If the test was performed with the same lot of chemical, I would tend to think it was a bad lot.

 

[Randy Holmes-Farley]

You might try taking a bucket of tank water, measure nitrate, add a fixed amount, then measure again and see if the values are reasonable.

Also, are you certain the dosed chemical was sodium nitrate and not sodium nitrite?

 

[Ryan15236]

You might try taking a bucket of tank water, measure nitrate, add a fixed amount, then measure again and see if the values are reasonable.

Also, are you certain the dosed chemical was sodium nitrate and not sodium nitrite?

Good idea. I will keep you updated if I do this. I’m going to retest this evening or tomorrow and get sample from refugium again and see if this gets similar results as the 3.7 ppm from this morning

One sample essentially not reacting with reagent and then next sample extremely overreacting baffles me unless truly bad batch

I can believe 3.7 PPM if being diligent with socks has that dramatic of effect over last 1.5 weeks

 

[Ryan15236]

I tested tonight and took sample from DT instead. Test results = 40.3ppm

Could this number be true? I got a similar number about two weeks ago before last WC. If so, why such a discrepancy between sample taken from refugium (3ppm) vs 40.3 ppm)
Refugium is after filter socks and skimmer

 

[Randy Holmes-Farley]

I tested tonight and took sample from DT instead. Test results = 40.3ppm

Could this number be true? I got a similar number about two weeks ago before last WC. If so, why such a discrepancy between sample taken from refugium (3ppm) vs 40.3 ppm)
Refugium is after filter socks and skimmer

A refugium will typically have about the same nitrate as the display if there is any reasonable flow between them.

As noted, there may be testing issues.

 

[Ryan15236]

I tested tonight and took sample from DT instead. Test results = 40.3ppm

Could this number be true? I got a similar number about two weeks ago before last WC. If so, why such a discrepancy between sample taken from refugium (3ppm) vs 40.3 ppm)
Refugium is after filter socks and skimmer

A refugium will typically have about the same nitrate as the display if there is any reasonable flow between them.

As noted, there may be testing issues.

Sicce 4.0 rated for 951 gph should be sufficient and jebao running around 250gph in skimmer compartment feeds a UV.

You had asked if I was sure I was dosing sodium nitrate and yes I ordered some of the food grade product from Amazon.

I’ll continue to test more frequently but I’ll probably order more reagent or contact Hanna. These numbers are everywhere

 

[BryanM]

Sicce 4.0 rated for 951 gph should be sufficient and jebao running around 250gph in skimmer compartment feeds a UV.

You had asked if I was sure I was dosing sodium nitrate and yes I ordered some of the food grade product from Amazon.

I’ll continue to test more frequently but I’ll probably order more reagent or contact Hanna. These numbers are everywhere

I'd just get more reagant, do a couple tests, and if that stabilizes, toss the current stock.

 

[Tangdora]

Are you using the same dosing syringe that you are dosing your nitrate solution with to draw the tank water itself.

 

[gbroadbridge]

Good idea. I will keep you updated if I do this. I’m going to retest this evening or tomorrow and get sample from refugium again and see if this gets similar results as the 3.7 ppm from this morning

One sample essentially not reacting with reagent and then next sample extremely overreacting baffles me unless truly bad batch

I can believe 3.7 PPM if being diligent with socks has that dramatic of effect over last 1.5 weeks

Try a different test kit. Salifert for example.

 

[Ryan15236]

Are you using the same dosing syringe that you are dosing your nitrate solution with to draw the tank water itself.

No but I will pick up some new clean ones today

 

[Ryan15236]

Good idea. I will keep you updated if I do this. I’m going to retest this evening or tomorrow and get sample from refugium again and see if this gets similar results as the 3.7 ppm from this morning

One sample essentially not reacting with reagent and then next sample extremely overreacting baffles me unless truly bad batch

I can believe 3.7 PPM if being diligent with socks has that dramatic of effect over last 1.5 weeks

Try a different test kit. Salifert for example.

I have an old API I could try

 

[Amstar]

have you tried a LFS to see what their test shows compared to yours? take water from the same area/source for your test and your LFS to see how they compare --

 

[Ryan15236]

Tested this morning.
Hanna checker results 36.7ppm. Similar results to 40.7ppm from Tuesday 10/28
However I did use an API nitrate test and looks to me to be zero. Curious on thoughts here? Also trying to decide on how much water change based of results normally 20% every 2 weeks.

 

[Randy Holmes-Farley]

I personally believe the nitrate is adequate, but try the Hanna on some new salt water that presumably is low in nitrate.

 

[Ryan15236]

I personally believe the nitrate is adequate, but try the Hanna on some new salt water that presumably is low in nitrate.

Will do. I will continue WC as normal and test my batch of new saltwater before change to confirm