Testing For Phosphates (Simple Question)
- Thread starter 64Ivy
- Start date
Kutter
Premium Member
I've been using the Salifert Phosphate kit which has always tested 0 for phosphate, yet I still had hair algae (also tested negative for Nitrates). I added a Phosphate sponge into my empty canister filter and my hair algae improved, so there was definitely some phosphates I wasn't picking up with the Salifert kit in the water.
Your inorganic phosphate kit will detect organic phosphate. The sample just needs special treatment to do so. If you boil the sample with a strong acid, such as sulfuric, in the presence of an oxidizing agent, potassium persulfate is often used, then you will convert most organic phosphates to simple inorganic phosphate. The result with your test kit will then be for total phosphate. Simply subtract the untreated sample result from the total result to get a general idea of the organic phosphate.
Habib at the Salifert forum can help. Total phosphate test kits are also available from Hach Chemical.
Habib at the Salifert forum can help. Total phosphate test kits are also available from Hach Chemical.
tatuvaaj said:
Jeez-Louise, fellas! Any way to do this WITHOUT having to wear a hazmat suit and evacuating the block?
I mean, if I've got to tell the wife I'm using her microwave to boil sulfuric acid, I'm not only sleeping on the couch, I'm sleeping on YOUR couch!
64Ivy said:Jeez-Louise, fellas! Any way to do this WITHOUT having to wear a hazmat suit and evacuating the block?
:lol: We never told you guys this chemistry stuff was easy!! :lol:
Sorry but the organophosphate compounds must be destroyed and the phosphate released as simple orthophosphate for the test to work, hence the need to boil it under acidic oxidizing conditions. Short of that you only detect inorganic forms. Some methods use a UV oxidation method to convert organic to simple phosphates but I don't know how effective that is.
Nano6,
In the digested sample the phosphate assimilated by the algae is released and can be determined.
For what it is worth--on tests on my own tank I have often seen close to zero values for inorganic phosphate but obtained values of 0.6- 1.3 ppm of organic phosphate after digestion. The higher values are normally on unfiltered samples where algae could indeed play a roll in the higher numbers
MiddletonMark
Premium Member
Will trade couch for frags :lmao:
MIKE NY
Two Decade club
I'm at point now that I don't even test for PO4 now because it's always a reading of zero, but there is algae so I know it's there. I use indicators to determine how much.....such as the obvious algaes that bloom and how often I have to clean the front glass. The only true acurate measurement would be from a colorimeter for only around $1500....and I would be on my couch too....out at the curb.
:lol:
Even with a spectrophotometer you would still need the pretreatment to convert complex phosphates into ortho. The ascorbic acid reduction method, the most commonly used, can only detect simple inorganic phosphate. One of the pretreatment steps I talked about earlier in this thread is still required to get total phosphate. Boiling in a somewhat acidic solution can convert metaphosphates/ polyphosphates to ortho but organic phosphates don't respond.
Even with a spectrophotometer you would still need the pretreatment to convert complex phosphates into ortho. The ascorbic acid reduction method, the most commonly used, can only detect simple inorganic phosphate. One of the pretreatment steps I talked about earlier in this thread is still required to get total phosphate. Boiling in a somewhat acidic solution can convert metaphosphates/ polyphosphates to ortho but organic phosphates don't respond.
