# Where does PO4 come from



## H.. (15 Mar 2016)

I allways dend to have very high levels of PO4 in the tank, and I allso have quite an high ammoumt of livestock, but also quite a lots of plants too.

Yes I know PO4 comes from the food we give to the live stock. But does it come from elsewere? 

I keep large roots, mangrove type, and offcourse they tend to rotten, but does they give away any PO4? 

And in the bottom layer, is there an depot of PO4 there? I have only sand and gravel. But the tanks are very old and filters are big.

How much PO4 is there in 100 grams of pellets or flakes. I use tetra pro´s flakes in an eheim feeder to feed onece a day, and refill every two weeks. max 1 dl/2weeks  

I do 50% waterchanges every two week all year around, pretty good growth, due to Fe and KNO3 ferts, but never PO4. And the levels of PO4 is almost always way over 1,8ppm. When I get a lots of algeas like BBA there is high levels of PO4, and when I try to give small amounts of PO4 in ferts i get more BBA

Where do my PO4 come from?

Thanks for taking time to read.

H.


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## H.. (15 Mar 2016)

No co2 in the tanks. 

I have quite some tanks and they do best when PO4 is as low as possible


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## Greenfinger2 (15 Mar 2016)

Hi H...

https://en.wikipedia.org/wiki/Phosphate


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## zozo (15 Mar 2016)

Meats and fish which is always a substance in the foods,  is the phosphate source, now i'm not a chemist and won't throw around with numbers and symbols. But from what i understand it is not readily available as phosphate. Phosphate is a byproduct from the nitrification process of waste products, such as left over foods, fish poop and other detritus. So it can come from the decaying organic matter in your soil as most obvious source.. So if you don't put P in as fert, it probably is the feeding. You might try to cut that down a bit and skip a day.. Or clean the substrate more often and better.

There can also be a little P in the tap water.

From what information i can find and probaly also a lot written about here at UKAPS and other forums even with explainations to a high standard of scientific degree. PO4 does in fact not contribute to algae bloom, it's rather the lak of co2 doing this.. Amonium which also is a by product in the nitrogen cycle seems to trigger more algae growth than phosphate does. 

Edit:
http://www.barrreport.com/forum/barr-report/co2-enrichment/3479-does-too-much-phosphate-cause-algae


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## dw1305 (15 Mar 2016)

Hi all, 





H.. said:


> I do 50% waterchanges every two week all year around


It might come from the water change water, if you use tap water?

I'm not sure about Europe outside of the EU, but because limits on lead (Pb) in drinking water are very tight in the EU (10 μg/l since 2013) and tap water suppliers will add PO4--- to the water supply to precipitate out any Pb++ ions as insoluble lead phosphate complexes.

From: Final Report of the Drinking water inspectorate:
 Demonstration of Optimisation of<"Plumbosolvency Treatment and Control Measures">


> _In England and Wales, treatment to reduce plumbosolvency generally consists of dosing orthophosphoric acid or a sodium orthophosphate to achieve a target concentration that is usually in the range 1 to 2 mg/l as P. The pH may also be adjusted although the effectiveness of orthophosphate is relatively insensitive to pH. Increasing the orthophosphate concentration reduces the solubility of lead but the additional benefits of increasing the dose diminish as the dose is increased._


This is the current situation <"UK WATER INDUSTRY RESEARCH LIMITED: ALTERNATIVES TO PHOSPHATE FOR PLUMBOSOLVENCY CONTROL">





> _Alternatives to phosphate dosing to meet the new lead standard far out weight the current cost of phosphate dosing and without remediation of customer supply lead pipes will be unlikely to achieve compliance..............Phosphate dosing reduces the measured lead concentrations at the tap substantially. Mean phosphate dosing concentrations across all zones for any given water company ranged from 0.7 mg-P/l to 1.9 mg-P/l, leading to a current rate of compliance with the10 μg/l standard of approximately 99%..."_


Cheers Darrel


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## PARAGUAY (15 Mar 2016)

If as Darrel suggests could be the tapwater and your not using CO2 injection you could use Polyfilter or a product like Cleanwater to reduce levels


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## ian_m (16 Mar 2016)

How are you determining your PO4 level. I do hope you are using something like a LaMotte Phosphate test kit
http://www.coleparmer.co.uk/Product/LaMotte_Phosphate_test_kit_low_range_0_to_3_0_ppm/UY-99565-17
and not something you bought in a fish shop?

These hobby kits are notoriously unreliable and results are influenced by other salts/chemicals present in the water sample. Hobby phosphate test kits are possibly affected by chloride (giving false positive) in the water as well as dechlorinators and ammonia.

Quite a few people report getting positive PO4 results even though they know it should be 0ppm.


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## zozo (16 Mar 2016)

ian_m said:


> How are you determining your PO4 level. I do hope you are using something like a LaMotte Phosphate test kit
> http://www.coleparmer.co.uk/Product/LaMotte_Phosphate_test_kit_low_range_0_to_3_0_ppm/UY-99565-17
> and not something you bought in a fish shop?
> 
> ...



That's a pretty darn expensive test kit..  
I have no idea what the costs are but might be worth to give a company like this a call and ask the price of an analysis report..
Doing analisys for plant nurseries is their bussines, so you probably don't even have to say t them what to look for, they probably know already.
http://www.relabdenhaan.com/Pages/Content/Default.aspx?L=2&P=117


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## dw1305 (16 Mar 2016)

Hi all, 





ian_m said:


> How are you determining your PO4 level. I do hope you are using something like a LaMotte Phosphate test kit


"ian_m" is right measuring orthophosphate (PO4---) isn't straight forward.

We use spectrophotometry with either the vandomolybdate reagent (read at 400nm), or stannous chloride (read at 800nm), it depends upon the level of PO4--- in the water.  Details are here <"Determination of phosphorus concentration.......">. We use the different wavelengths to the quoted ones because we have a scanning spec. that allows us to measure the peak absorbance.

Once or twice I've run water samples that people have sent me (using the stannous chloride method) and they have just gone off the standard curve (usually the maximum standard we use is 3 ppm, because the relationship between PO4 and absorbance becomes non-linear after that).

I haven't diluted the samples, mainly because they have been a really dark blue, and that tells me that they have a minimum of 10ppm PO4 in them (and probably quite a lot more than that).

cheers Darrel


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