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measuring GH and water board problems

Corbie

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Long established (29 years) 140 litre tank, plants and small community fish all doing well, with CO2 and two Fluval G3s including activated carbon, regularly replaced. I’ve been lucky in that our tap water has historically been near perfect, pH 7, very low NO3, medium GH but low KH, chlorine not noticeable, for years. The tank substrate is sand / gravel / mulm and occasional root tabs. We recently had some work done on the local water mains, and they have really messed with our water- it’s now pH 8.4 out the tap, high nitrates and hard water, heavily chlorinated. I’ve no idea what they could have done to mess it up so badly! It’s a soft water area. Unfortunately, I only discovered this after a 15% water change.

I use an Apera PC60 pH & EC meter, and the G3s also track EC. The other parameters are tested with API test strips.

10 days ago (after the tank water change), these were the readings in the tank: pH 7.5, GH 180ppm, KH 80ppm, NO3 80ppm, NO2 3ppm, EC 1400+. All higher than normal, with the EC rocketed. I started a daily water change, 15% per day. I’ve also invested in a reverse osmosis kit and so all replaced water is R/O. No additives for now. I’ve fed fish sparingly, flake only. After 10 days of this, the readings are approaching what they were before: pH 6.7, GH 180, KH 40, NO2 0, NO3 <20, EC 840. So, successful to a degree. All fish and plants seem oblivious to all the changes.

I’ve tested the R/O water, which is as expected, just water, readings zero. My question is, the GH has apparently not changed, although the electrical conductivity has nearly halved. Why not? Reading the help guides, I guess the answer might be “ditch the test strips!”
 

dw1305

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Hi all,
We recently had some work done on the local water mains, and they have really messed with our water- it’s now pH 8.4 out the tap, high nitrates and hard water, heavily chlorinated.
Welcome to UKAPS, unfortunately have a few of <"these threads">.

Your water probably isn't actually any harder, in terms of carbonate buffering (dKH), the water companies use <"sodium hydroxide (NaOH) to raise pH">. Unless it is supply from a totally different source I would suspect the test kit for the high NO3 reading. I'm not a great fan of nitrate testing, it isn't that it isn't important but it is <"more problematic"> than most aquarium based literature acknowledges.

Can you <"collect rain-water">? I've used since the 1970s without any problem, I'm <"pretty risk adverse"> and I consider it a lot safer than tap water.
After 10 days of this, the readings are approaching what they were before: pH 6.7, GH 180, KH 40, NO2 0, NO3 <20, EC 840.
The <"electrical conductivity value is a bit strange">, if it is reading in "microS"? it is really high, if it is a <"reading in "ppm TDS?"> it is absolutely astronomical.
........ For my tanks (I keep Apistogramma etc.), I keep the water in the 50 - 150 microS range.

cheers Darrel
 
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Corbie

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Hi all,

Welcome to UKAPS, unfortunately have a few of <"these threads">. Your water probably isn't actually any harder, in terms of carbonate buffering (dKH), the water companies use <"sodium hydroxide (NaOH) to raise pH">. Unless it is supply from a totally different source I would suspect the test kit for the high NO3 reading. I'm not a great fan of nitrate testing, it isn't that it isn't important but it is <"more problematic"> than most aquarium based literature acknowledges.

Can you <"collect rain-water">? I've used since the 1970s without any problem, I'm <"pretty risk adverse"> and I consider it a lot safer than tap water.

The <"electrical conductivity value is a bit strange">, if it is reading in "microS"? it is really high, if it is a <"reading in "ppm TDS?"> it is absolutely astronomical.


cheers Darrel
Thanks Darrel. I'm sorry, I should have read a bit more before posting. The EC is in microS. The same meter reads TDS as slightly less than 1/2 that value, about 400ppm. But yes, still pretty high, and a bit to go to bring it down to normal. However it's always been quite high. I'm puzzled as to why the EC readings have halved yet the GH (test strip) reading has stayed the same. Re rain water, yes, can do that, but I have the R/O unit now so can be more precise with what I'm adding.
All academic because fish and plants are thriving, thankfully. I'm just trying to improve my education ;)
 

dw1305

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H all,
All academic because fish and plants are thriving, thankfully.
Good, that is the main thing.
The EC is in microS. The same meter reads TDS as slightly less than 1/2 that value, about 400ppm.
Interesting, the TDS should be at <"least 1/2 the EC value in microS">.
I'm puzzled as to why the EC readings have halved yet the GH (test strip) reading has stayed the same.
It will be another ion, dGH is only a measure of calcium (Ca++) and magnesium (Mg++) ions, the EC is a measure of all the ions in solution.
However it's always been quite high.
I don't know why, have you always re-mineralised your tap water?

cheers Darrel
 

Corbie

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Interesting, the TDS should be at <"least 1/2 the EC value in microS">.
If measured at the same time ;)
It will be another ion, dGH is only a measure of calcium (Ca++) and magnesium (Mg++) ions, the EC is a measure of all the ions in solution.
Thanks. But replacing the water with R/O water, without additives, should result in a dilution of all dissolved ions, should it not? Including Ca++ and Mg++.
I don't know why, have you always re-mineralised your tap water?
The tank is in its 29th year and I have never re-mineralised my tap water. I've not had the R/O kit very long, and planned to start remineralising R/O water (not tap water) once I got conditions back nearer to normal.
cheers Darrel
 

dw1305

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Hi all,
But replacing the water with R/O water, without additives, should result in a dilution of all dissolved ions, should it not? Including Ca++ and Mg++.
Definitely should.
The tank is in its 29th year and I have never re-mineralised my tap water. I've not had the R/O kit very long, and planned to start remineralising R/O water (not tap water) once I got conditions back nearer to normal.
I'm at a loss to explain why the conductivity is so high.

cheers Darrel
 
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dw1305

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Hi all,
There is certainly a wealth of information on this forum.
That is the one great advantage of UKAPS, there are plenty of <"useful posts"> and <"tutorials">.

We've been a well run forum (thank you @LondonDragon and moderators @Ady34 and @GHNelson etc) we've mainly been fairly polite to one another, even when we haven't always agreed, and we just have great posters (@Geoffrey Rea , @foxfish , @Tim Harrison , @ceg4048 , @Wookii , @Zeus.) who have many years of practical experience. We have aquascapers (@George Farmer, @CooKieS), we have members with scientific technical knowledge (@oreo57 and @X3NiTH) etc., we have growers of rare plants (@Roland), I could go on and apologies to those I missed (@sparkyweasel, @alto and @shangman etc).

I'm biased, but I don't think there is another repository of as much practical and scientifically accurate advice and information about planted tank keeping on the WWW.

cheers Darrel
 

dw1305

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Hi all,
Have you checked the calibration of the meter?
Definitely worth checking. You can calibration solutions for these meters, the <"442 standard"> is the usual one for freshwater,
........ 442 Natural Water Standard Solutions are based on the following salt proportions: 40% sodium sulfate, 40% sodium bicarbonate, and 20% sodium chloride which represent the three predominant components
“anions” in freshwater). This salt ratio has conductivity characteristics approximating fresh natural waters ............
or you can <"make your own fairly easily">.

cheers Darrel
 

MichaelJ

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Definitely worth checking.
For testing my TDS meter (not calibrating) I use one gram of NaCl (table salt) in one liter of distilled water. Stir thoroughly and measure. My TDS in the salt solution comes out at some where between 990-1010... close enough for all intended purposes.
 
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Geoffrey Rea

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Wouldn’t Inductively Coupled Plasma (ICP) water analysis of tank and tap water be worth considering at this point?

We recently had some work done on the local water mains, and they have really messed with our water- it’s now pH 8.4 out the tap, high nitrates and hard water, heavily chlorinated. I’ve no idea what they could have done to mess it up so badly! It’s a soft water area.

Have you asked the water company for an explanation regarding the change in parameters?
 

Corbie

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Have you asked the water company for an explanation regarding the change in parameters?
I tried... the person I finally spoke to at Scottish Water didn't seem to know much about water. But she did tell me that the work they did recently involved rerouting, to bypass an area with lots of deteriorating pipework. I asked if that could mean that our water is now coming from a different source, and she said yes, but couldn't tell me anything else.
As an update on the situation, none of the fish, nor plants, seem any the wiser. All seem good and healthy and behaving normally. With my new R/O kit I've been gradually replacing water, 20l per day (tank is 140l), and EC has now come down to around 600 (TDS 384 ppm). I plan to keep going a bit further, and then start on an Estimated Index programme to make sure all the trace elements are there, and because it's new to me and I'm intrigued to see what will happen. I'll post a few pics on the journals section.
 

X3NiTH

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I’ll take a stab at suggesting the water work done somewhere has used a cement that is leaching as it cures, if it is a hydraulic cement and low in leachate then the water should improve over the next few weeks to months depending on the size of works carried out, if your on a new supply then that could be coming from a recently constructed/repaired storage facility (Dam works).

Stab in the dark but it’s my best guess.

:)
 
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