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Just got a TDS Meter. A new approach to my Low Tech.

si walker

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Hi.
That's a Millimetre.
I suspect that most TDS meters look slightly disappointing inside. It's the bag of crisps affect!! Big and flash only.
I'm only asking for a ball park figure which I hope that I am achieving.

By the way did you replace your TDS METER?

Thanks
 

jaypeecee

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By the way did you replace your TDS METER?
Hi @si walker

The HM Digital was intended as a backup to my trusty (and old) Hanna DIST 3 conductivity meter, which is what I continue to use. There have been several threads about TDS meters here on UKAPS in the last few months. I suggest that you do a search using the magnifying glass icon at the top RHS of your screen.

JPC
 

_Maq_

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to make sure your TDS remains stable over time - that you don't have any large increases that suggest build-up of waste
TDS - in fact, conductivity - is rather unreliable here. Many organic compounds - the waste - dissolve un-ionized and do not affect conductivity. Only after complete mineralization they get fully ionized.
 

jaypeecee

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Many organic compounds - the waste - dissolve un-ionized and do not affect conductivity. Only after complete mineralization they get fully ionized.

And, the word 'mineralization' was a word that I struggled with for quite a long time. Mineralization, as I see it, is the process by which heterotrophic bacteria and other decomposers, in general (including funghi) convert organic compounds into inorganic compounds, very often inorganic phosphate (PO4^3-). Do we all agree on that?

JPC
 
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John q

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Tds isn't exact science... but it gives shall we say a suggestion. Obviously you could stare into a glass ball and see which way the prevailing wind blows if that's more accurate 🤔
 
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_Maq_

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Mineralization, as I see it, is the process by which heterotrophic bacteria and other decomposers, in general (including funghi) convert organic compounds into inorganic compounds, very often inorganic phosphate (PO4^3-). Do we all agree on that?
Yes.
Yet you mentioned orthophosphate rather unfortunately. Phosphorus is always in short supply, or, used to be before EI was invented. Microbes tend to keep all phosphorus for themselves. Fortunately, they die within hours, and plants can get what they need through their roots. Often assisted by mycorrhizal fungi.
Tds isn't exact science... but it gives shall we say a suggestion.
You can compare numbers in time-line. But comparing measurements with other people is misleading because there's no binding formula for converting conductivity to TDS. Each and every TDS meter can do it differently. This is the reason for which I strongly suggest measuring conductivity instead.
 

jaypeecee

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Yes.
Yet you mentioned orthophosphate rather unfortunately.
Hi @_Maq_

You've lost me there. Why do you consider my mention of orthophosphate to be rather unfortunate?

Microbes tend to keep all phosphorus for themselves. Fortunately, they die within hours...

Yes, and when the microbes die, orthophosphate (PO4^3-) re-enters the water column and is recycled. From measurements that I have made with Java Fern, uptake of PO4^3- is rapid (minutes, not hours). And, luxury uptake ensures that PO4^3- is thoroughly removed. All living creatures need phosphorus to synthesize ATP*, as I understand it.

* Adenosine Triphosphate

JPC
 

_Maq_

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You've lost me there. Why do you consider my mention of orthophosphate to be rather unfortunate? ... Yes, and when the microbes die, orthophosphate (PO4^3-) re-enters the water column and is recycled.
Unfortunate because phosphorus cycling is very ambivalent, and scientists are still struggling with elucidation of many details. Anyway, largest share of phosphorus remains bound in organic compounds, in most situations. So, mineralization of phosphorus-containing organic compounds ideally ends in the form of orthophosphate, indeed, but you can seldom find any...
 

jaypeecee

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So, mineralization of phosphorus-containing organic compounds ideally ends in the form of orthophosphate, indeed, but you can seldom find any...

For anyone who is allergic to science, you may be wise to skip what awaits you below...:geek:

Hi @_Maq_ & Everyone

I have no difficulty detecting orthophosphate, i.e. PO4^3- in my tanks. The JBL Phosphate Sensitive Test Kit measures down to <0.02 mg/litre. I also have a Hanna HI713 Colorimeter which measures down to 0.05 mg/litre. I have accumulated a lot of papers, etc, related to this topic. Here's one that you may find useful:


Whilst on the topic of phosphorus and bacteria, you may find the following to be interesting. It's taken from the irreplaceable The Krib. It's a discussion group before the days of forums:


I find the following to be particularly useful:


All four sections in 'Phosphorus and Phosphorus Control' are well worth reading - in my opinion. Here is an example:

Phosphatase is an enzyme that bacteria use to convert DPo* and PPo** to
DPi.*** Some algae may also have that ability. Alkaline phosphatase - which
works when the pH is near and above 7 - is the most well documented form
of phosphatase. There is also an acid phosphatase that doesn't seem to be
as well documented. Phosphatase activity increases with the size of the
bacterial population; activity is promoted by oxygen and suppressed by
dissolved phosphate.

Bacteria typically produce more phosphate than they consume, and that can
lead to an excess of phosphate in the water.

The phosphatase-catalyzed reaction from PPo to DPi should be discouraged
to prevent production of excess dissolved phosphate. If the reaction can
be slowed down then phosphorus will remain in the detritus where it can be
more easily siphoned off before it causes problems.

And, finally:

"The conditions that promote high levels of phosphatase activity and so cause
rapid release of phosphorus from detritus are exactly the conditions found
in aquarium filters. In a filter, organic particulates are trapped in a
constant flow of aerated water where a large population of bacteria can
act on the detritus. The flowing water also flushes the phosphate
released by the reaction, which otherwise could suppress further
phosphatase activity. So removing a filter should reduce the phosphatase
activity.

I keep unfiltered tanks. I think in retrospect that pulling the filters
off my tanks helped control phosphate levels, but I can't substantiate
that.

It will be interesting to get feedback from UKAPS members on the above. Do people agree with the points being made by Roger S. Miller and others?

I am really keen to hear what UKAPS members have to say. My stance is neutral as a lot of what is being said is new to me.

*DPo = Dissolved Organic Phosphorus

**PPo = Particulate Organic Phosphorus

***DPi = Dissolved Inorganic Phosphorus

Now, give yourself a well-deserved pat on the back if you've managed to read this far!!

JPC
 
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