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



## si walker (2 May 2022)

Hi.
In the time given I have read as much as possible on Low Tech. Some of the most wonderful examples on this site (Shangman- "The Mossy Spider" for example) always commented how they are quite relaxed about adding fertilisers and only topping up if they are too busy drinking tea! On the other hand there I am chucking ferts at my tank on a daily basis. I don't even run CO2 and feel that I lost my way a bit.
Anyway I am taking a new approach from today by using a TDS Meter.
Basically I will measure my tap water.
Do a water change- measure that.
Add a couple days worth of ferts- measure that.
Over the week I will continue to measure and try to grasp how my plants are using the supplies that I offer them.
Personally I'm quite looking forward to this rather that just adding more and more. Its Low Tech after all and I presume the uptake is slower than what I expect?
Let me know if you are doing something along the same lines.

Si


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## MichaelJ (2 May 2022)

si walker said:


> Hi.
> In the time given I have read as much as possible on Low Tech. Some of the most wonderful examples on this site (Shangman- "The Mossy Spider" for example) always commented how they are quite relaxed about adding fertilisers and only topping up if they are too busy drinking tea! On the other hand there I am chucking ferts at my tank on a daily basis. I don't even run CO2 and feel that I lost my way a bit.
> Anyway I am taking a new approach from today by using a TDS Meter.
> Basically I will measure my tap water.
> ...



Hi @si walker, Using the TDS meter to gauge plant uptake is going to be difficult. A good portion of what you add in terms of fish food and the waste from fish, snails, plant decay etc.  will show up as TDS.  So unless your running a plant-only tank there is generally no way you can tell from the number what the plants uptake is (its different in a high tech tank where the uptake might be much higher).  What you do want is to make sure your TDS remains stable over time - that you don't have any large increases that suggest build-up of waste - that is mainly how I utilize my TDS meter - I just want things to remain stable at the TDS levels I have dialed in with my water parameters and weekly fertilizers.  Generally you don't need much fertilizer in a low tech tank and of course your fertilizer regime is up to you and will work as long as you don't starve your plants on any of the essential nutrients.

Cheers,
Michael


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## Djoko Sauza (2 May 2022)

I use somewhat of a similar method in order to keep TDS very low since I have blackwater fish. Here goes: since I use a dosing pump I know how much ppm of salts is being added per week (13ppm at the moment - still lowering from starting point of 30ppm). If my TDS increases by more than say 5ppm by the end of the week I'll reduce the amount of ferts dosed. To make things more complicated, the amount of floaters, at least in my case, also plays a major role in the amount of nutrients being consumed.
After using EI for many years I'm now testing how*   lean* I can go before all my plants melt one by one. I can say already after losing a few plants: not recommended if you want to have a nice planted tank.

If my goal was to keep only plants happy then I wouldn't push the lower boundary of nutrient availability so hard and accept that some unused nutrient accumulation is not a big deal. In any case, using a TDS meter to check what is going on with your water is in my eyes always a good idea. I think your method is sound but only if you keep an eye on your plants as well, they will tell you if you've gone too lean before the TDS meter.


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## erwin123 (3 May 2022)

I used to have more time to maintain my hightech and lowtech tank, but as I'm back at office most of the time, I have less time for tank maintenance - my hightech needs the maintenance routine so I've been sort of neglecting my lowtech.

For the lowtech, I am doing monthly water change for my lowtech and dosing ferts when I feel like it. I also haven't trimmed the plants for a month or so.... but the plants are ok and the tank hasn't crashed.😅 There is no BBA whatsoever despite such poor maintenance, and the only algae is GDA on the glass which I can just scrape off ....


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## MichaelJ (3 May 2022)

erwin123 said:


> For the lowtech, I am doing monthly water change for my lowtech and dosing ferts when I feel like it. I also haven't trimmed the plants for a month or so.... but the plants are ok and the tank hasn't crashed.😅 There is no BBA whatsoever despite such poor maintenance, and the only algae is GDA on the glass which I can just scrape off ....


In that case that doesn't sound like poor maintenance to me necessarily.  The reason I change (~30-40%) water weekly in my tanks is mostly for the sake of my livestock and not the plants - if I had plant-only tanks or extremely lightly stocked tanks, I am sure I would and could go for a lot longer...

Cheers,
Michael


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## si walker (6 May 2022)

Thank you for your feedback!
I will post up my weekly PPM when I'm done. 
On day 5 so far, the PPM has not moved. 
In simple terms I understand this as the ferts put in 4 days ago have yet to be consumed? 
This is a possibility as it is a low tech tank and my lighting is set for 6 hours. 
Or the ferts are all gone and it has been replaced with the same exact amount of fish waste, which I doubt as the tank water has been measured daily with no fluctuations .
I love this kind of things and look forward to reading some opinions on what else could possibly be happening/or not happening as it were!
Cheers.


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## Djoko Sauza (6 May 2022)

What plants do you have and how is their growth rate? Are you topping up the water to account for evaporation if you're using an open top?


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## si walker (6 May 2022)

Djoko Sauza said:


> What plants do you have and how is their growth rate? Are you topping up the water to account for evaporation if you're using an open top?


Hi. Well i am in week one of using the TDS Meter so it is early days. Tank heavily planted (nearly full!) I have a lid so very little evaporation. Plants good. Tank mates all good.


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## si walker (20 May 2022)

Okay so I said that I would report back on this one.
Still doing TDS readings daily.
Okay I admit that I'm confused about this. My PPM reading has been at 260 give or take, for the last two weeks?
Does this mean that the Fertilisers put in there at the beginning have not been consumed ? I have not added anymore and only topped the water up by about 500ml.

Let me know what you all think? Remember that theres no CO2. 

Thanks for reading.


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## hypnogogia (20 May 2022)

Presumably you are feeding you fish?  Whilst ferts get consumed, y the food you add will also contribute to your TDS.


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## si walker (20 May 2022)

hypnogogia said:


> Presumably you are feeding you fish?  Whilst ferts get consumed, y the food you add will also contribute to your TDS.


I am yes! Which leads to why the TDS remains constant. The paranoid in me wants to dump a load of ferts in the tank!


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## dw1305 (20 May 2022)

Hi all, 


si walker said:


> The paranoid in me wants to dump a load of ferts in the tank!


As some of your floating plants are <"looking a bit peaky"> I would definitely <"add some fertiliser">. 

It can be a relatively low dosage, but I'd use a complete mix.

cheers Darrel


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## jaypeecee (20 May 2022)

si walker said:


> On day 5 so far, the PPM has not moved.





si walker said:


> My PPM reading has been at 260 give or take, for the last two weeks?





si walker said:


> Which leads to why the TDS remains constant.


Hi @si walker 

Something's amiss and I suspect that you have a faulty TDS meter. You should be seeing some variation in your readings. May I ask the manufacturer's name and model number of your TDS meter? There are a lot of dodgy TDS meters out there.

JPC


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## brhau (20 May 2022)

si walker said:


> Okay I admit that I'm confused about this. My PPM reading has been at 260 give or take, for the last two weeks?


Did you establish a daily baseline (over a week or so) for the TDS before adding ferts and then see it jump up to 260 after dosing?


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## si walker (20 May 2022)

brhau said:


> Did you establish a daily baseline (over a week or so) for the TDS before adding ferts and then see it jump up to 260 after dosing?


Yes I did. I also measured my tap water etc.
I do have low light and run at 6 hours only. Maybe it is super slow tech?


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## si walker (20 May 2022)

jaypeecee said:


> Hi @si walker
> 
> Something's amiss and I suspect that you have a faulty TDS meter. You should be seeing some variation in your readings. May I ask the manufacturer's name and model number of your TDS meter? There are a lot of dodgy TDS meters out there.
> 
> JPC


Yeah I thought so too. 
Actually this evening I reloaded the tank with ferts. It's only 35 litres and for each MM I put in the TDS Meter jumped consistently 2 ppm, which I take as being pretty accurate. 
I have the HM Digital TDS-3.
It is by no means a professional one!

Thanks for your reply.


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## brhau (20 May 2022)

si walker said:


> Yes I did. I also measured my tap water etc.
> I do have low light and run at 6 hours only. Maybe it is super slow tech?


There are too many unknowns here, such as what all the measurements are and what the tank looks like. Is it possible that ferts weren't the limiting factor before you dosed?

As pointed out above, TDS is a noisy number, especially since you're well above blackwater levels. When I've tried this in the past, I measured nitrate to determine the minimum dosing regime. If I dose above that, I can measure the unconsumed nitrate.  That was a more sensitive measure than TDS. I know the accuracy of nitrate test kits is questionable, but it at least seems repeatable in my hands.


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## si walker (20 May 2022)

Funny you say that as I too measure nitrate. Mine is off the charts! Crazy high right out of the tap. Also like my Po4.


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## brhau (20 May 2022)

OK, so if your nitrates and PO4 are sky high, maybe your plants aren't hungry for ferts?


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## jaypeecee (20 May 2022)

si walker said:


> Actually this evening I reloaded the tank with ferts. It's only 35 litres and for each MM I put in the TDS Meter jumped consistently 2 ppm, which I take as being pretty accurate.
> I have the HM Digital TDS-3.


Hi @si walker 

Just for clarification, what do you mean by 'MM'?

I used to have an HM Digital TDS-3. But, I had to return it for a full refund. The stick-on membrane with the push buttons was starting to peel away from the meter body. I'd had it for just over a week. I was able to see the electronic circuitry inside - through the gap! Very disappointing. 

JPC


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## si walker (20 May 2022)

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


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## jaypeecee (20 May 2022)

si walker said:


> 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


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## _Maq_ (29 Jul 2022)

MichaelJ said:


> 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.


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## jaypeecee (29 Jul 2022)

_Maq_ said:


> 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 (29 Jul 2022)

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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## jaypeecee (29 Jul 2022)

John q said:


> Obviously you could stare into a glass ball and see which way the prevailing wind blows if that's more accurate 🤔



Isn't that meteorology?  

JPC


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## _Maq_ (30 Jul 2022)

jaypeecee said:


> 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.


John q said:


> 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.


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## jaypeecee (1 Aug 2022)

_Maq_ said:


> 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?



_Maq_ said:


> 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


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## _Maq_ (1 Aug 2022)

jaypeecee said:


> 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...


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## jaypeecee (3 Aug 2022)

_Maq_ said:


> 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...

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:









						Aquatic heterotrophic bacteria have highly flexible phosphorus content and biomass stoichiometry - The ISME Journal
					

Bacteria are central to the cycling of carbon (C), nitrogen (N) and phosphorus (P) in every ecosystem, yet our understanding of how tightly these cycles are coupled to bacterial biomass composition is based upon data from only a few species. Bacteria are commonly assumed to have high P content...




					www.nature.com
				




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:



			[The Krib] Aquatic Plants
		


I find the following to be particularly useful:



			Phosphorus
		


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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