How long after dosing silicates is phophate testing reliable ?

[taricha]

I’ve read there are no reliable SI tests, which is why I never bought one. Do you know of any ?

Hanna (or hach) Si works great. I used the
https://www.hannainst.com/hi705-silica-lr.html

 

[Randy Holmes-Farley Verified Community Expert]

I used the Hach and never had a reason to doubt it.

 

[taricha]

Just to make sure hanna didn't change their PO4 chemistry and develop a sudden hypersensitivity to Si, I re-checked.

I pulled a liter of tank water.
Initial tank water - hanna ULR reads 16ppb P (0.05ppm PO4) , hanna LR Si 0.43 ppm SiO2.
I dosed +2.0ppm Si (4.2ppm SIO2) from brightwell spongexcel to the Liter of water.
the P value after was 26 ppb (0.08ppm PO4).
(API PO4 read zero yellow the whole time, unsurprisingly)

This is in line with the data I posted above. +4ppm SiO2 generates a barely detectable increase in measured PO4 value.

@Idech I'm not sure why your hanna tests are giving you false high readings in the order of ~a ppm PO4, but it's not a few ppm of Si that's causing the problem. My guess is that when you get a new batch of hanna PO4 reagents the mystery will go away.

 

[Miami Reef]

Just to make sure hanna didn't change their PO4 chemistry and develop a sudden hypersensitivity to Si, I re-checked.

I pulled a liter of tank water.
Initial tank water - hanna ULR reads 16ppb P (0.05ppm PO4) , hanna LR Si 0.43 ppm SiO2.
I dosed +2.0ppm Si (4.2ppm SIO2) from brightwell spongexcel to the Liter of water.
the P value after was 26 ppb (0.08ppm PO4).
(API PO4 read zero yellow the whole time, unsurprisingly)

This is in line with the data I posted above. +4ppm SiO2 generates a barely detectable increase in measured PO4 value.

@Idech I'm not sure why your hanna tests are giving you false high readings in the order of ~a ppm PO4, but it's not a few ppm of Si that's causing the problem. My guess is that when you get a new batch of hanna PO4 reagents the mystery will go away.

Thank you, Taricha, for doing the experiment again! You are so helpful! :star-struck:

 

[Idech]

@Idech I'm not sure why your hanna tests are giving you false high readings in the order of ~a ppm PO4, but it's not a few ppm of Si that's causing the problem. My guess is that when you get a new batch of hanna PO4 reagents the mystery will go away.

Hmm. Maybe I’ll order a new batch then.

 

[Randy Holmes-Farley Verified Community Expert]

Nice job, Taricha!

 

[Idech]

@taricha I just got a new batch of Hanna reagents today. Here are the tests results :

1- Hanna ULR phosphate (new reagent) : 0,8 ppm
2- Hanna ULR phosphate (old reagent, recently bought) : 0,58 ppm
3- Salifert : 0 ppm pr close to 0

So I really don’t know what to think. My corals are not doing well.

I am waiting for new reagent to test alkalinity because it tested 6,5 dkh and I think it’s not right (I made a mistake while handling the reagent and might have contaminated it).

So between the alk, the phosphate and the high magnesium (1560 ppm), I’m not sure what’s causing my problems.

I wish I had someone to test for me but I don’t. So the mystery continues…

 

[taricha]

Sorry you've been going in circles on this for so long. :-(

For the sake of my sanity, if I can verify with my tests that my new saltwater is in acceptable parameters, I'd do water changes until my tank water started testing with sane results also.


Debugging chemistry test kit errors can take a really long time and be a massive headache if what you really want is just want to have happy livestock.

 

[Idech]

Sorry you've been going in circles on this for so long. :-(

For the sake of my sanity, if I can verify with my tests that my new saltwater is in acceptable parameters, I'd do water changes until my tank water started testing with sane results also.


Debugging chemistry test kit errors can take a really long time and be a massive headache if what you really want is just want to have happy livestock.

I wish I could do a massive WC, but even a small one brings back dinos that I’ve been chasing away for 7 months.

I’m really at a loss here. If I do a WC, I’ll have to dose more silicates, which started my phosphate testing problems in the first place.

I feel so stuck. :-(

 

[Idech]

Update : I can confirm the Hanna ULR phosphate checker gives false readings when dosing silicates. I’ve just had an ICP test and my phosphate levels are 0.03 but my Hanna checker showed 0.9 ppm (while 2 other tests showed close to 0).

On some reefing Facebook group about dinos, they are saying the Hanna LR phosphate checker, which uses a different reagent, remain accurate while dosing.

 

[Dan_P]

Update : I can confirm the Hanna ULR phosphate checker gives false readings when dosing silicates. I’ve just had an ICP test and my phosphate levels are 0.03 but my Hanna checker showed 0.9 ppm (while 2 other tests showed close to 0).

On some reefing Facebook group about dinos, they are saying the Hanna LR phosphate checker, which uses a different reagent, remain accurate while dosing.

The ICP test may not provide reliable phosphorous values.

 

[Idech]

The ICP test may not provide reliable phosphorous values.

We have to trust something, sometime. Everything can’t be wrong just because it’s hard to believe this Hanna reagent reacts with silicates.

If it was anecdotal, maybe. But it’s not; many reefers are talking about it, not just me.

 

[Dan_P]

We have to trust something, sometime. Everything can’t be wrong just because it’s hard to believe this Hanna reagent reacts with silicates.

If it was anecdotal, maybe. But it’s not; many reefers are talking about it, not just me.

What would be convincing data is taking a sample of aquarium water, measuring the PO4 level 3 times, then dosing silicate to whatever level you wish, measure the silicate concentration to confirm the silicate concentration and then test the PO4 again 3 times. The replicates are needed because most folks are not so clear about test variation, thinking different readings mean an effect where in reality it is test variation. Have I missed this sort of data?

 

[Idech]

What would be convincing data is taking a sample of aquarium water, measuring the PO4 level 3 times, then dosing silicate to whatever level you wish, measure the silicate concentration to confirm the silicate concentration and then test the PO4 again 3 times. The replicates are needed because most folks are not so clear about test variation, thinking different readings mean an effect where in reality it is test variation. Have I missed this sort of data?

I haven’t see any such data. But honestly, for me, my own experience suffices as I’ve seen this happen over and over again.

You can see my silicate levels above. They are 3333% over the ideal value. I’m not dosing anymore in my tank, lol !

 

[taricha]

We have to trust something, sometime. Everything can’t be wrong just because it’s hard to believe this Hanna reagent reacts with silicates.

Thanks for the ICP test. It shows 5 ppm Si = ~11 ppm SiO2. This is over 5x the max level of my hanna Si checker so not something I think many people would hit.

Which hanna reagents do you suspect do and don't have super high PO4 interference?

 

[Idech]

Thanks for the ICP test. It shows 5 ppm Si = ~11 ppm SiO2. This is over 5x the max level of my hanna Si checker so not something I think many people would hit.

Which hanna reagents do you suspect do and don't have super high PO4 interference?

According to this person on the Facebook reefer group who has both the ULR (the one I use) and the LR Hanna phosphate checker, the LR checker is still accurate even with high levels of silicates. The LR uses a different reagent than the ULR checker.

Maybe I’ll buy the LR checker because it’s going to be a while before my silicate levels drop to undetectable levels, or at least very low.

 

[taricha]

The LR uses a different reagent than the ULR checker.

Maybe I’ll buy the LR checker because it’s going to be a while before my silicate levels drop to undetectable levels, or at least very low.

thanks.
I never found high Si sensitivity in the ULR P packets. And there's no reason to think they are different than the ULR PO4 ones.
But please try out the packets you expect to work and update us. (hint: you can buy packets without a checker)

@Dan_P interestingly, in the F-M test posted above, PO4 was measured with ICP and photometrically, with neither registering much PO4.

 

[Idech]

thanks.
I never found high Si sensitivity in the ULR P packets. And there's no reason to think they are different than the ULR PO4 ones.
But please try out the packets you expect to work and update us. (hint: you can buy packets without a checker)

@Dan_P interestingly, in the F-M test posted above, PO4 was measured with ICP and photometrically, with neither registering much PO4.

Are you saying I could buy the LR reagents and use them in my ULR checker ?

 

[Miami Reef]

Are you saying I could buy the LR reagents and use them in my ULR checker ?

No. Taricha said that the ultra-low phosphorus kit uses the same reagent as the ultra-low phosphate.

 

[TWYOUNG]

I'm in the early stage of testing this out but I've been dosing 2 mls Na+ silicate daily for two weeks in my 150gal system, and while Hanna ULR results are running quite high, Hanna LR have been matching up with Nyos at much lower values. I get values of near 0.2 on the ULR when the other two are close to the zero values I've been struggling to raise for weeks.