Hair/Black Beard Algae help please!

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
I use the JBL PO4 (sensitive) test kit which is obviously (?) measuring the inorganic phosphate ion (orthophosphate)
I'm pretty sure that will give you a reasonably accurate value for PO4---. I think this is a test which <"goes blue">?
A sample containing the phosphate is mixed with an acid solution of MoVI, for example ammonium molybdate, to produce PMo12O3−40, which has an α-Keggin structure. This anion is then reduced by, for example, ascorbic acid or SnCl2, to form the blue coloured β-keggin ion, PMo12O7−40.[5] The amount of the blue coloured ion produced is proportional to the amount of phosphate present and the absorption can be measured using a colorimeter to determine the amount of phosphorus
I'd be honest and say that I would be surprised, if any-one who uses tap water in the UK, suffers much in the way of phosphate deficiency. As far as I know all UK tap water is treated with orthophosphoric acid (or sodium phosphate) which supplies an excess of phosphorus ions that will react with any lead (Pb) or copper (Cu) ions in the water. The technical term is <"control of plumbosolvency">.

They <"add phosphorus to our tap water">, even though it comes out of a deep-limestone aquifer and is heavily carbonate buffered.

cheers Darrel
 

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,469
Location
Bracknell
Hi all, I'm pretty sure that will give you a reasonably accurate value for PO4---. I think this is a test which <"goes blue">?

Hi @dw1305

Yes, the JBL PO4 Sensitive Test Kit goes blue as PO4 is detected. It's good to be reassured that I can rely on it. I wonder if it's a re-branded Macherey-Nagel Visocolor ECO kit? Both JBL and the latter are German companies.

JPC
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
The normal protocol is to drink the gin, then wether or not it is red or gray seems less important.
........and you've just doubled the value of the (now designer) gin by infusing it with a novel botanical.

It might take a little while to turn red.
I wonder if it's a re-branded Macherey-Nagel Visocolor ECO kit? Both JBL and the latter are German companies.
It could be. It is the same basic methodology.

My guess would be that hobby grade kits probably use reagents that are relatively non-toxic and that can be disposed of down the sink.

I should also have said that I would routinely dilute the sample 50:50 with DI water and then filter it through a fine grade filter paper. Ideally you want the samples to read about 1/2 way along the <"linear section of your standard curve">. We decolourise the water samples, but that would only be a minor issue with aquarium water, unless it was tannin stained.

cheers Darrel
 

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,469
Location
Bracknell
It could be. It is the same basic methodology.

My guess would be that hobby grade kits probably use reagents that are relatively non-toxic and that can be disposed of down the sink.

I should also have said that I would routinely dilute the sample 50:50 with DI water and then filter it through a fine grade filter paper. Ideally you want the samples to read about 1/2 way along the <"linear section of your standard curve">. We decolourise the water samples, but that would only be a minor issue with aquarium water, unless it was tannin stained.

Hi @dw1305

Thanks for the additional information. I no longer have access to lab-grade filter papers. Would an unbleached (brown) coffee filter do the trick?

JPC
 

dw1305

Expert
Joined
7 Apr 2008
Messages
10,971
Location
nr Bath
Hi all,
Would an unbleached (brown) coffee filter do the trick?
Give it a go. It should get the bigger particles out. It is really only if you measure absorbance with a spectrophotometer that it becomes important. That is one advantage of the <"molybdenum blue"> method, it is fairly robust with tinted water, because the water is unlikely to have any blue coloured pollutants (that interfere at ~890 nm).

The yellow method........
Vanadate/molybdate method (yellow method) In acids, ortho-phosphate ions react with ammonium molybdate and ammonium vanadate to form yellow ammonium phosphoric vanadomolybdate. This can be photometrically analyzed at 380 nm.
.....Needs filtering and decolourising more carefully.

cheers Darrel
 

Similar threads

Top