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Low KH, high TDS ?

erwin123

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My TDS will be slightly off because I had to change 5 litres (half a bucket of water) to do some cleaning.

after WC before dosing - 120-125 (can't remember exactly)
after dosing: didn't record

day 2
after dosing: 130

day 3 (changed 5 litres of water before measruement)
before dosing 125
after dosing 130

My meter showing a 5pm change looks reasonably accurate give or take a few ppm because my dosing is roughly 3.5ppm based on my calculations.
But I am surprised that TDS didn't change that much from the day before. Anyway, I have the whole week to check.
 

eminor

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Day 2 : 200 ppm before light and co2 start

it seems okay so far right ?
 

eminor

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If you did not dose ferts on day 2 any particular reason for 20ppm increase in 1 day?

Day 1: 180ppm
Day 2: 200ppm (no dosing?)
day 2, just micro which should be less than 1 ppm, the 20 ppm could that be CO2 ? maybe not because it will go out with light off ?

sometimes i put rain water in because it's open top so evaporation, could be that too, rain water is 20 ppm but i only add a bit it can't explain the 20 ppm jump
 
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erwin123

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day 2, just micro which should be less than 1 ppm, the 20 ppm could that be CO2 ? maybe not because it will go out with light off ?

sometimes i put rain water in because it's open top so evaporation, could be that too, rain water is 20 ppm but i only add a bit it can't explain the 20 ppm jump

If the 20ppm is unexplained it might be a problem - maybe not the ppm itself, but the substance that is causing this increased 20ppm reading, or alternatively, the 20ppm is from something harmless, in which case it is not a problem. But as you pointed out, it can't be from your fertiliser dosing.

If you top up 180ppm water in your tank with 20ppm water, the ppm of the water should drop, not increase.
 

jaypeecee

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Hi Folks,

I just quickly scanned this thread - so, ignore me if this point has already been made - is the dissolved CO2 contributing to the electrical conductivity? If so, this would show up on a 'TDS' meter. Just a thought.

JPC
 

eminor

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If the 20ppm is unexplained it might be a problem - maybe not the ppm itself, but the substance that is causing this increased 20ppm reading, or alternatively, the 20ppm is from something harmless, in which case it is not a problem. But as you pointed out, it can't be from your fertiliser dosing.

If you top up 180ppm water in your tank with 20ppm water, the ppm of the water should drop, not increase.
i see, where the hell the 20 ppm come from, cannot be from the soil, innert sand, i clean it every week before water change,
 

erwin123

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Hi Folks,

I just quickly scanned this thread - so, ignore me if this point has already been made - is the dissolved CO2 contributing to the electrical conductivity? If so, this would show up on a 'TDS' meter. Just a thought.

JPC

Just wondering, if you take the TDS reading at the same time every day, wouldn't the amount of dissolved CO2 be the same? i.e. the TDS increase has to be due to something else? This assumes that eminor is taking his TDS reading at the same time each day. (myself, I dose ferts daily around the same time before lights on), so thats when I check TDS.
 

John q

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is the dissolved CO2 contributing to the electrical conductivity
As far as I'm aware the tds change from the inclusion of co2 is minimal, don't have anything to reference at hand but would be suprised if it adds 2~3 ppm difference from lights to lights off.
 

jaypeecee

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As far as I'm aware the tds change from the inclusion of co2 is minimal, don't have anything to reference at hand but would be suprised if it adds 2~3 ppm difference from lights to lights off.
Hi @John q

You may well be correct. But this has piqued my interest and I feel that I should know more about it. I will therefore run an experiment - or two!

JPC
 

John q

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Hi @John q

You may well be correct. But this has piqued my interest and I feel that I should know more about it. I will therefore run an experiment - or two!

JPC
Yes piqued my interest also, I've tested tds from co2 on to off and had very minimal change.

Your like me @jaypeecee we need to see, before we believe. Suspect the issue is related to solids, dissolved solids, and or solutions .
 
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jaypeecee

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Yes piqued my interest also, I've tested tds from co2 on to off and had very minimal change.

Your like me @jaypeecee we need to see, before we believe.
Hi @John q

I also did a simple experiment. As my CO2 cylinders are in use on tanks, I tried the Heath Robinson approach...

I popped my conductivity meter into 100ml of RO water. The reading was 5 microS/cm. Then, I exhaled a few times via some 4mm tubing into the water. After about five exhalations, the conductivity had risen to 11 microS/cm. Clearly, the exhaled CO2 was forming carbonic acid, H2CO3 (as I expected) and this increased electrical conductivity. Nothing earth-shattering there.

I would be interested in knowing a few more details about your experiment, e.g. volume of water, CO2 injection rate, CO2 ON duration, etc.

All the best.

JPC
 

John q

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I would be interested in knowing a few more details about your experiment, e.g. volume of water, CO2 injection rate, CO2 ON duration, etc.
No worries jpc.

Having read on the "Web" co2 increases tds I ran this test.

240l tank with a low inital tds. Checked reading before gas on, tds around 170, ph 7.3. Injection rate through the roof, only had 1 internal diffuser at this time.

4hrs later ph was at 6.4, lights came on, tds reading was 171.
I don't use a fancy tds meter, so results should be taken with a pinch of salt.

I'm sure the guru's on this site will explain why co2 plays no part in raising tds levels (the science behind it) I'm not a guru, I'm thick.

Merry Christmas jpc 😘
 

MichaelJ

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Hi @eminor Please post a full tank shot, so we can see what's going on with respect to plant mass, hard scape, substate etc. also what media are you using in your filter. Any bit of information may help to shed light on this. Are you adding anything else to the tank besides food and traces during the week? and what food and what fish?

Merry Christmas to all,
Michael
 
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John q

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Then, I exhaled a few times via some 4mm tubing into the water. After about five exhalations, the conductivity had risen to 11 microS/cm. Clearly, the exhaled CO2 was forming carbonic acid, H2CO3 (as I expected) and this increased electrical conductivity. Nothing earth-shattering there.
Just an after thought. We also exhale nitrogen and carbon monoxide, amongst other gases. Maybe this contributed to total tds in your test?
 
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eminor

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Hi @eminor Please post a full tank shot, so we can see what's going on with respect to plant mass, hard scape, substate etc. also what media are you using in your filter. Any bit of information may help to shed light on this. Are you adding anything else to the tank besides food and traces during the week? and what food and what fish?

Merry Christmas to all,
Michael

there is pictures of sand, filter,

i removed noodles since ceg told me that was the biggest influence on the flow, so in the filter so basically there's only those foam, there are big enough i think, could that be the issue ?

i trimmed plants yesterday

51vBzSp6ogS._SL500_.jpg


i spotted a co2 deficiency on a plant recently I think that's because i reduced the co2 level due to fish gasping, i fixed it i think

20211224_183416.jpg

Other deficiency here on the crypt i think ?

20211224_183150.jpg

too much co2 ? can still see green in it, hardly on pictures

20211224_182546.jpg
 

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jaypeecee

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Having read on the "Web" co2 increases tds I ran this test.
Hi @John q

Confusion arises because the term 'TDS' is misleading in this context. A TDS meter does not measure total dissolved solids. Instead it measures electrical conductivity and then estimates Total Dissolved Solids based on assumptions made about the composition of the water. In order to actually measure Total Dissolved Solids, it is necessary to drive off water at elevated temperature and then weigh the residue. That's why bubbling CO2 through water appears to increase TDS (because it increases electrical conductivity).

Hope that clarifies things.

JPC
 
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